| | | | | | | | | | | | | | | | | | | | | |
<?xml version="1.0" encoding="windows-1252"?> |
<FilingSummary> |
| <Version> 3.19.1 </Version> |
| <ProcessingTime/> |
| <ReportFormat> html </ReportFormat> |
| <ContextCount> 511 </ContextCount> |
| <ElementCount> 442 </ElementCount> |
| <EntityCount> 1 </EntityCount> |
| <FootnotesReported> true </FootnotesReported> |
| <SegmentCount> 147 </SegmentCount> |
| <ScenarioCount> 0 </ScenarioCount> |
| <TuplesReported> false </TuplesReported> |
| <UnitCount> 9 </UnitCount> |
| <MyReports> |
| | <Report instance="ck0000839759-20181231.xml"> |
| | | <IsDefault> false </IsDefault> |
| | | <HasEmbeddedReports> false </HasEmbeddedReports> |
| | | <HtmlFileName> R1.htm </HtmlFileName> |
| | | <LongName> 1001 - Document - Document and Entity Information </LongName> |
| | | <ReportType> Sheet </ReportType> |
| | | <Role> http://imetrix.edgar-online.com/taxonomy/role/DocumentandEntityInformation </Role> |
| | | <ShortName> Document and Entity Information </ShortName> |
| | | <MenuCategory> Cover </MenuCategory> |
| | | <Position> 1 </Position> |
| | | </Report> |
| | <Report instance="ck0000839759-20181231.xml"> |
| | | <IsDefault> false </IsDefault> |
| | | <HasEmbeddedReports> false </HasEmbeddedReports> |
| | | <HtmlFileName> R2.htm </HtmlFileName> |
| | | <LongName> 1003 - Statement - Statements of Operations and Comprehensive Income </LongName> |
| | | <ReportType> Sheet </ReportType> |
| | | <Role> http://imetrix.edgar-online.com/taxonomy/role/StatementOfIncomeInsuranceBasedRevenue </Role> |
| | | <ShortName> Statements of Operations and Comprehensive Income </ShortName> |
| | | <MenuCategory> Statements </MenuCategory> |
| | | <Position> 2 </Position> |
| | | </Report> |
| | <Report instance="ck0000839759-20181231.xml"> |
| | | <IsDefault> false </IsDefault> |
| | | <HasEmbeddedReports> false </HasEmbeddedReports> |
| | | <HtmlFileName> R3.htm </HtmlFileName> |
| | | <LongName> 1004 - Statement - Statements of Operations and Comprehensive Income (Parenthetical) </LongName> |
| | | <ReportType> Sheet </ReportType> |
| | | <Role> http://imetrix.edgar-online.com/taxonomy/role/StatementOfIncomeInsuranceBasedRevenueParenthetical </Role> |
| | | <ShortName> Statements of Operations and Comprehensive Income (Parenthetical) </ShortName> |
| | | <MenuCategory> Statements </MenuCategory> |
| | | <Position> 3 </Position> |
| | | </Report> |
| | <Report instance="ck0000839759-20181231.xml"> |
| | | <IsDefault> false </IsDefault> |
| | | <HasEmbeddedReports> false </HasEmbeddedReports> |
| | | <HtmlFileName> R4.htm </HtmlFileName> |
| | | <LongName> 1005 - Statement - Statements of Financial Position </LongName> |
| | | <ReportType> Sheet </ReportType> |
| | | <Role> http://imetrix.edgar-online.com/taxonomy/role/StatementOfFinancialPositionUnclassified-InvestmentBasedOperations </Role> |
| | | <ShortName> Statements of Financial Position </ShortName> |
| | | <MenuCategory> Statements </MenuCategory> |
| | | <Position> 4 </Position> |
| | | </Report> |
| | <Report instance="ck0000839759-20181231.xml"> |
| | | <IsDefault> false </IsDefault> |
| | | <HasEmbeddedReports> false </HasEmbeddedReports> |
| | | <HtmlFileName> R5.htm </HtmlFileName> |
| | | <LongName> 1006 - Statement - Statements of Financial Position (Parenthetical) </LongName> |
| | | <ReportType> Sheet </ReportType> |
| | | <Role> http://imetrix.edgar-online.com/taxonomy/role/StatementOfFinancialPositionUnclassified-InvestmentBasedOperationsParenthetical </Role> |
| | | <ShortName> Statements of Financial Position (Parenthetical) </ShortName> |
| | | <MenuCategory> Statements </MenuCategory> |
| | | <Position> 5 </Position> |
| | | </Report> |
| | <Report instance="ck0000839759-20181231.xml"> |
| | | <IsDefault> false </IsDefault> |
| | | <HasEmbeddedReports> false </HasEmbeddedReports> |
| | | <HtmlFileName> R6.htm </HtmlFileName> |
| | | <LongName> 1007 - Statement - Statements of Shareholder's Equity </LongName> |
| | | <ReportType> Sheet </ReportType> |
| | | <Role> http://imetrix.edgar-online.com/taxonomy/role/StatementOfShareholdersEquityAndOtherComprehensiveIncome </Role> |
| | | <ShortName> Statements of Shareholder's Equity </ShortName> |
| | | <MenuCategory> Statements </MenuCategory> |
| | | <Position> 6 </Position> |
| | | </Report> |
| | <Report instance="ck0000839759-20181231.xml"> |
| | | <IsDefault> false </IsDefault> |
| | | <HasEmbeddedReports> false </HasEmbeddedReports> |
| | | <HtmlFileName> R7.htm </HtmlFileName> |
| | | <LongName> 1008 - Statement - Statements of Cash Flows </LongName> |
| | | <ReportType> Sheet </ReportType> |
| | | <Role> http://imetrix.edgar-online.com/taxonomy/role/StatementOfCashFlowsIndirectInvestmentBasedOperations </Role> |
| | | <ShortName> Statements of Cash Flows </ShortName> |
| | | <MenuCategory> Statements </MenuCategory> |
| | | <Position> 7 </Position> |
| | | </Report> |
| | <Report instance="ck0000839759-20181231.xml"> |
| | | <IsDefault> false </IsDefault> |
| | | <HasEmbeddedReports> false </HasEmbeddedReports> |
| | | <HtmlFileName> R8.htm </HtmlFileName> |
| | | <LongName> 1009 - Disclosure - General </LongName> |
| | | <ReportType> Sheet </ReportType> |
| | | <Role> http://imetrix.edgar-online.com/taxonomy/role/NotesToFinancialStatementsOrganizationConsolidationAndPresentationOfFinancialStatementsDisclosureTextBlock </Role> |
| | | <ShortName> General </ShortName> |
| | | <MenuCategory> Notes </MenuCategory> |
| | | <Position> 8 </Position> |
| | | </Report> |
| | <Report instance="ck0000839759-20181231.xml"> |
| | | <IsDefault> false </IsDefault> |
| | | <HasEmbeddedReports> false </HasEmbeddedReports> |
| | | <HtmlFileName> R9.htm </HtmlFileName> |
| | | <LongName> 1010 - Disclosure - Summary of Significant Accounting Policies </LongName> |
| | | <ReportType> Sheet </ReportType> |
| | | <Role> http://imetrix.edgar-online.com/taxonomy/role/NotesToFinancialStatementsSignificantAccountingPoliciesTextBlock </Role> |
| | | <ShortName> Summary of Significant Accounting Policies </ShortName> |
| | | <MenuCategory> Notes </MenuCategory> |
| | | <Position> 9 </Position> |
| | | </Report> |
| | <Report instance="ck0000839759-20181231.xml"> |
| | | <IsDefault> false </IsDefault> |
| | | <HasEmbeddedReports> false </HasEmbeddedReports> |
| | | <HtmlFileName> R10.htm </HtmlFileName> |
| | | <LongName> 1011 - Disclosure - Supplemental Cash Flow Information </LongName> |
| | | <ReportType> Sheet </ReportType> |
| | | <Role> http://imetrix.edgar-online.com/taxonomy/role/NotesToFinancialStatementsCashFlowSupplementalDisclosuresTextBlock </Role> |
| | | <ShortName> Supplemental Cash Flow Information </ShortName> |
| | | <MenuCategory> Notes </MenuCategory> |
| | | <Position> 10 </Position> |
| | | </Report> |
| | <Report instance="ck0000839759-20181231.xml"> |
| | | <IsDefault> false </IsDefault> |
| | | <HasEmbeddedReports> false </HasEmbeddedReports> |
| | | <HtmlFileName> R11.htm </HtmlFileName> |
| | | <LongName> 1012 - Disclosure - Related Party Transactions </LongName> |
| | | <ReportType> Sheet </ReportType> |
| | | <Role> http://imetrix.edgar-online.com/taxonomy/role/NotesToFinancialStatementsRelatedPartyTransactionsDisclosureTextBlock </Role> |
| | | <ShortName> Related Party Transactions </ShortName> |
| | | <MenuCategory> Notes </MenuCategory> |
| | | <Position> 11 </Position> |
| | | </Report> |
| | <Report instance="ck0000839759-20181231.xml"> |
| | | <IsDefault> false </IsDefault> |
| | | <HasEmbeddedReports> false </HasEmbeddedReports> |
| | | <HtmlFileName> R12.htm </HtmlFileName> |
| | | <LongName> 1013 - Disclosure - Investments </LongName> |
| | | <ReportType> Sheet </ReportType> |
| | | <Role> http://imetrix.edgar-online.com/taxonomy/role/NotesToFinancialStatementsInvestmentTextBlock </Role> |
| | | <ShortName> Investments </ShortName> |
| | | <MenuCategory> Notes </MenuCategory> |
| | | <Position> 12 </Position> |
| | | </Report> |
| | <Report instance="ck0000839759-20181231.xml"> |
| | | <IsDefault> false </IsDefault> |
| | | <HasEmbeddedReports> false </HasEmbeddedReports> |
| | | <HtmlFileName> R13.htm </HtmlFileName> |
| | | <LongName> 1014 - Disclosure - Fair Value of Assets and Liabilities </LongName> |
| | | <ReportType> Sheet </ReportType> |
| | | <Role> http://imetrix.edgar-online.com/taxonomy/role/NotesToFinancialStatementsFairValueDisclosuresTextBlock </Role> |
| | | <ShortName> Fair Value of Assets and Liabilities </ShortName> |
| | | <MenuCategory> Notes </MenuCategory> |
| | | <Position> 13 </Position> |
| | | </Report> |
| | <Report instance="ck0000839759-20181231.xml"> |
| | | <IsDefault> false </IsDefault> |
| | | <HasEmbeddedReports> false </HasEmbeddedReports> |
| | | <HtmlFileName> R14.htm </HtmlFileName> |
| | | <LongName> 1015 - Disclosure - Derivative Financial Instruments and Off-balance sheet Financial Instruments </LongName> |
| | | <ReportType> Sheet </ReportType> |
| | | <Role> http://imetrix.edgar-online.com/taxonomy/role/NotesToFinancialStatementsDerivativeFinancialInstrumentsAndOffBalanceSheetFinancialInstrumentsDisclosureTextBlock </Role> |
| | | <ShortName> Derivative Financial Instruments and Off-balance sheet Financial Instruments </ShortName> |
| | | <MenuCategory> Notes </MenuCategory> |
| | | <Position> 14 </Position> |
| | | </Report> |
| | <Report instance="ck0000839759-20181231.xml"> |
| | | <IsDefault> false </IsDefault> |
| | | <HasEmbeddedReports> false </HasEmbeddedReports> |
| | | <HtmlFileName> R15.htm </HtmlFileName> |
| | | <LongName> 1016 - Disclosure - Reserve for Life-Contingent Contract Benefits and Contractholder Funds </LongName> |
| | | <ReportType> Sheet </ReportType> |
| | | <Role> http://imetrix.edgar-online.com/taxonomy/role/NotesToFinancialStatementsReserveForLifeContingentContractBenefitsAndContractholderFundsDisclosureTextBlock </Role> |
| | | <ShortName> Reserve for Life-Contingent Contract Benefits and Contractholder Funds </ShortName> |
| | | <MenuCategory> Notes </MenuCategory> |
| | | <Position> 15 </Position> |
| | | </Report> |
| | <Report instance="ck0000839759-20181231.xml"> |
| | | <IsDefault> false </IsDefault> |
| | | <HasEmbeddedReports> false </HasEmbeddedReports> |
| | | <HtmlFileName> R16.htm </HtmlFileName> |
| | | <LongName> 1017 - Disclosure - Reinsurance </LongName> |
| | | <ReportType> Sheet </ReportType> |
| | | <Role> http://imetrix.edgar-online.com/taxonomy/role/NotesToFinancialStatementsReinsuranceTextBlock </Role> |
| | | <ShortName> Reinsurance </ShortName> |
| | | <MenuCategory> Notes </MenuCategory> |
| | | <Position> 16 </Position> |
| | | </Report> |
| | <Report instance="ck0000839759-20181231.xml"> |
| | | <IsDefault> false </IsDefault> |
| | | <HasEmbeddedReports> false </HasEmbeddedReports> |
| | | <HtmlFileName> R17.htm </HtmlFileName> |
| | | <LongName> 1018 - Disclosure - Deferred Policy Acquisition and Sales Inducement Costs </LongName> |
| | | <ReportType> Sheet </ReportType> |
| | | <Role> http://imetrix.edgar-online.com/taxonomy/role/NotesToFinancialStatementsDeferredPolicyAcquisitionCostsAndSalesInducementCostsDisclosureTextBlock </Role> |
| | | <ShortName> Deferred Policy Acquisition and Sales Inducement Costs </ShortName> |
| | | <MenuCategory> Notes </MenuCategory> |
| | | <Position> 17 </Position> |
| | | </Report> |
| | <Report instance="ck0000839759-20181231.xml"> |
| | | <IsDefault> false </IsDefault> |
| | | <HasEmbeddedReports> false </HasEmbeddedReports> |
| | | <HtmlFileName> R18.htm </HtmlFileName> |
| | | <LongName> 1019 - Disclosure - Guarantees and Contingent Liabilities </LongName> |
| | | <ReportType> Sheet </ReportType> |
| | | <Role> http://imetrix.edgar-online.com/taxonomy/role/NotesToFinancialStatementsCommitmentsContingenciesAndGuaranteesTextBlock </Role> |
| | | <ShortName> Guarantees and Contingent Liabilities </ShortName> |
| | | <MenuCategory> Notes </MenuCategory> |
| | | <Position> 18 </Position> |
| | | </Report> |
| | <Report instance="ck0000839759-20181231.xml"> |
| | | <IsDefault> false </IsDefault> |
| | | <HasEmbeddedReports> false </HasEmbeddedReports> |
| | | <HtmlFileName> R19.htm </HtmlFileName> |
| | | <LongName> 1020 - Disclosure - Income Taxes </LongName> |
| | | <ReportType> Sheet </ReportType> |
| | | <Role> http://imetrix.edgar-online.com/taxonomy/role/NotesToFinancialStatementsIncomeTaxDisclosureTextBlock </Role> |
| | | <ShortName> Income Taxes </ShortName> |
| | | <MenuCategory> Notes </MenuCategory> |
| | | <Position> 19 </Position> |
| | | </Report> |
| | <Report instance="ck0000839759-20181231.xml"> |
| | | <IsDefault> false </IsDefault> |
| | | <HasEmbeddedReports> false </HasEmbeddedReports> |
| | | <HtmlFileName> R20.htm </HtmlFileName> |
| | | <LongName> 1021 - Disclosure - Statutory Financial Information and Dividend Limitations </LongName> |
| | | <ReportType> Sheet </ReportType> |
| | | <Role> http://imetrix.edgar-online.com/taxonomy/role/NotesToFinancialStatementsStatutoryFinancialInformationAndDividendLimitationsDisclosureTextBlock </Role> |
| | | <ShortName> Statutory Financial Information and Dividend Limitations </ShortName> |
| | | <MenuCategory> Notes </MenuCategory> |
| | | <Position> 20 </Position> |
| | | </Report> |
| | <Report instance="ck0000839759-20181231.xml"> |
| | | <IsDefault> false </IsDefault> |
| | | <HasEmbeddedReports> false </HasEmbeddedReports> |
| | | <HtmlFileName> R21.htm </HtmlFileName> |
| | | <LongName> 1022 - Disclosure - Benefit Plans </LongName> |
| | | <ReportType> Sheet </ReportType> |
| | | <Role> http://imetrix.edgar-online.com/taxonomy/role/NotesToFinancialStatementsPensionAndOtherPostretirementBenefitsDisclosureTextBlock </Role> |
| | | <ShortName> Benefit Plans </ShortName> |
| | | <MenuCategory> Notes </MenuCategory> |
| | | <Position> 21 </Position> |
| | | </Report> |
| | <Report instance="ck0000839759-20181231.xml"> |
| | | <IsDefault> false </IsDefault> |
| | | <HasEmbeddedReports> false </HasEmbeddedReports> |
| | | <HtmlFileName> R22.htm </HtmlFileName> |
| | | <LongName> 1023 - Disclosure - Other Comprehensive Income </LongName> |
| | | <ReportType> Sheet </ReportType> |
| | | <Role> http://imetrix.edgar-online.com/taxonomy/role/NotesToFinancialStatementsComprehensiveIncomeNoteTextBlock </Role> |
| | | <ShortName> Other Comprehensive Income </ShortName> |
| | | <MenuCategory> Notes </MenuCategory> |
| | | <Position> 22 </Position> |
| | | </Report> |
| | <Report instance="ck0000839759-20181231.xml"> |
| | | <IsDefault> false </IsDefault> |
| | | <HasEmbeddedReports> false </HasEmbeddedReports> |
| | | <HtmlFileName> R23.htm </HtmlFileName> |
| | | <LongName> 1024 - Disclosure - Summary of Investments Other Than Investments in Related Parties </LongName> |
| | | <ReportType> Sheet </ReportType> |
| | | <Role> http://imetrix.edgar-online.com/taxonomy/role/NotesToFinancialStatementsSummaryOfInvestmentsOtherThanInvestmentsInRelatedPartiesTextBlock </Role> |
| | | <ShortName> Summary of Investments Other Than Investments in Related Parties </ShortName> |
| | | <MenuCategory> Notes </MenuCategory> |
| | | <Position> 23 </Position> |
| | | </Report> |
| | <Report instance="ck0000839759-20181231.xml"> |
| | | <IsDefault> false </IsDefault> |
| | | <HasEmbeddedReports> false </HasEmbeddedReports> |
| | | <HtmlFileName> R24.htm </HtmlFileName> |
| | | <LongName> 1025 - Disclosure - Reinsurance </LongName> |
| | | <ReportType> Sheet </ReportType> |
| | | <Role> http://imetrix.edgar-online.com/taxonomy/role/NotesToFinancialStatementsSupplementalScheduleOfReinsurancePremiumsForInsuranceCompaniesTextBlock </Role> |
| | | <ShortName> Reinsurance </ShortName> |
| | | <MenuCategory> Notes </MenuCategory> |
| | | <Position> 24 </Position> |
| | | </Report> |
| | <Report instance="ck0000839759-20181231.xml"> |
| | | <IsDefault> false </IsDefault> |
| | | <HasEmbeddedReports> false </HasEmbeddedReports> |
| | | <HtmlFileName> R25.htm </HtmlFileName> |
| | | <LongName> 1026 - Disclosure - Valuation Allowances and Qualifying Accounts </LongName> |
| | | <ReportType> Sheet </ReportType> |
| | | <Role> http://imetrix.edgar-online.com/taxonomy/role/NotesToFinancialStatementsScheduleOfValuationAndQualifyingAccountsDisclosureTextBlock </Role> |
| | | <ShortName> Valuation Allowances and Qualifying Accounts </ShortName> |
| | | <MenuCategory> Notes </MenuCategory> |
| | | <Position> 25 </Position> |
| | | </Report> |
| | <Report instance="ck0000839759-20181231.xml"> |
| | | <IsDefault> false </IsDefault> |
| | | <HasEmbeddedReports> false </HasEmbeddedReports> |
| | | <HtmlFileName> R26.htm </HtmlFileName> |
| | | <LongName> 1027 - Disclosure - Summary of Significant Accounting Policies (Policies) </LongName> |
| | | <ReportType> Sheet </ReportType> |
| | | <Role> http://imetrix.edgar-online.com/taxonomy/role/NotesToFinancialStatementsSignificantAccountingPoliciesTextBlockPolicies </Role> |
| | | <ShortName> Summary of Significant Accounting Policies (Policies) </ShortName> |
| | | <MenuCategory> Policies </MenuCategory> |
| | | <ParentRole> http://imetrix.edgar-online.com/taxonomy/role/NotesToFinancialStatementsSignificantAccountingPoliciesTextBlock </ParentRole> |
| | | <Position> 26 </Position> |
| | | </Report> |
| | <Report instance="ck0000839759-20181231.xml"> |
| | | <IsDefault> false </IsDefault> |
| | | <HasEmbeddedReports> false </HasEmbeddedReports> |
| | | <HtmlFileName> R27.htm </HtmlFileName> |
| | | <LongName> 1028 - Disclosure - General (Tables) </LongName> |
| | | <ReportType> Sheet </ReportType> |
| | | <Role> http://imetrix.edgar-online.com/taxonomy/role/NotesToFinancialStatementsOrganizationConsolidationAndPresentationOfFinancialStatementsDisclosureTextBlockTables </Role> |
| | | <ShortName> General (Tables) </ShortName> |
| | | <MenuCategory> Tables </MenuCategory> |
| | | <ParentRole> http://imetrix.edgar-online.com/taxonomy/role/NotesToFinancialStatementsOrganizationConsolidationAndPresentationOfFinancialStatementsDisclosureTextBlock </ParentRole> |
| | | <Position> 27 </Position> |
| | | </Report> |
| | <Report instance="ck0000839759-20181231.xml"> |
| | | <IsDefault> false </IsDefault> |
| | | <HasEmbeddedReports> false </HasEmbeddedReports> |
| | | <HtmlFileName> R28.htm </HtmlFileName> |
| | | <LongName> 1029 - Disclosure - Supplemental Cash Flow Information (Tables) </LongName> |
| | | <ReportType> Sheet </ReportType> |
| | | <Role> http://imetrix.edgar-online.com/taxonomy/role/NotesToFinancialStatementsCashFlowSupplementalDisclosuresTextBlockTables </Role> |
| | | <ShortName> Supplemental Cash Flow Information (Tables) </ShortName> |
| | | <MenuCategory> Tables </MenuCategory> |
| | | <ParentRole> http://imetrix.edgar-online.com/taxonomy/role/NotesToFinancialStatementsCashFlowSupplementalDisclosuresTextBlock </ParentRole> |
| | | <Position> 28 </Position> |
| | | </Report> |
| | <Report instance="ck0000839759-20181231.xml"> |
| | | <IsDefault> false </IsDefault> |
| | | <HasEmbeddedReports> false </HasEmbeddedReports> |
| | | <HtmlFileName> R29.htm </HtmlFileName> |
| | | <LongName> 1030 - Disclosure - Investments (Tables) </LongName> |
| | | <ReportType> Sheet </ReportType> |
| | | <Role> http://imetrix.edgar-online.com/taxonomy/role/NotesToFinancialStatementsInvestmentTextBlockTables </Role> |
| | | <ShortName> Investments (Tables) </ShortName> |
| | | <MenuCategory> Tables </MenuCategory> |
| | | <ParentRole> http://imetrix.edgar-online.com/taxonomy/role/NotesToFinancialStatementsInvestmentTextBlock </ParentRole> |
| | | <Position> 29 </Position> |
| | | </Report> |
| | <Report instance="ck0000839759-20181231.xml"> |
| | | <IsDefault> false </IsDefault> |
| | | <HasEmbeddedReports> false </HasEmbeddedReports> |
| | | <HtmlFileName> R30.htm </HtmlFileName> |
| | | <LongName> 1031 - Disclosure - Fair Value of Assets and Liabilities (Tables) </LongName> |
| | | <ReportType> Sheet </ReportType> |
| | | <Role> http://imetrix.edgar-online.com/taxonomy/role/NotesToFinancialStatementsFairValueDisclosuresTextBlockTables </Role> |
| | | <ShortName> Fair Value of Assets and Liabilities (Tables) </ShortName> |
| | | <MenuCategory> Tables </MenuCategory> |
| | | <ParentRole> http://imetrix.edgar-online.com/taxonomy/role/NotesToFinancialStatementsFairValueDisclosuresTextBlock </ParentRole> |
| | | <Position> 30 </Position> |
| | | </Report> |
| | <Report instance="ck0000839759-20181231.xml"> |
| | | <IsDefault> false </IsDefault> |
| | | <HasEmbeddedReports> false </HasEmbeddedReports> |
| | | <HtmlFileName> R31.htm </HtmlFileName> |
| | | <LongName> 1032 - Disclosure - Derivative Financial Instruments and Off-balance sheet Financial Instruments (Tables) </LongName> |
| | | <ReportType> Sheet </ReportType> |
| | | <Role> http://imetrix.edgar-online.com/taxonomy/role/NotesToFinancialStatementsDerivativeFinancialInstrumentsAndOffBalanceSheetFinancialInstrumentsDisclosureTextBlockTables </Role> |
| | | <ShortName> Derivative Financial Instruments and Off-balance sheet Financial Instruments (Tables) </ShortName> |
| | | <MenuCategory> Tables </MenuCategory> |
| | | <ParentRole> http://imetrix.edgar-online.com/taxonomy/role/NotesToFinancialStatementsDerivativeFinancialInstrumentsAndOffBalanceSheetFinancialInstrumentsDisclosureTextBlock </ParentRole> |
| | | <Position> 31 </Position> |
| | | </Report> |
| | <Report instance="ck0000839759-20181231.xml"> |
| | | <IsDefault> false </IsDefault> |
| | | <HasEmbeddedReports> false </HasEmbeddedReports> |
| | | <HtmlFileName> R32.htm </HtmlFileName> |
| | | <LongName> 1033 - Disclosure - Reserve for Life-Contingent Contract Benefits and Contractholder Funds (Tables) </LongName> |
| | | <ReportType> Sheet </ReportType> |
| | | <Role> http://imetrix.edgar-online.com/taxonomy/role/NotesToFinancialStatementsReserveForLifeContingentContractBenefitsAndContractholderFundsDisclosureTextBlockTables </Role> |
| | | <ShortName> Reserve for Life-Contingent Contract Benefits and Contractholder Funds (Tables) </ShortName> |
| | | <MenuCategory> Tables </MenuCategory> |
| | | <ParentRole> http://imetrix.edgar-online.com/taxonomy/role/NotesToFinancialStatementsReserveForLifeContingentContractBenefitsAndContractholderFundsDisclosureTextBlock </ParentRole> |
| | | <Position> 32 </Position> |
| | | </Report> |
| | <Report instance="ck0000839759-20181231.xml"> |
| | | <IsDefault> false </IsDefault> |
| | | <HasEmbeddedReports> false </HasEmbeddedReports> |
| | | <HtmlFileName> R33.htm </HtmlFileName> |
| | | <LongName> 1034 - Disclosure - Reinsurance (Tables) </LongName> |
| | | <ReportType> Sheet </ReportType> |
| | | <Role> http://imetrix.edgar-online.com/taxonomy/role/NotesToFinancialStatementsReinsuranceTextBlockTables </Role> |
| | | <ShortName> Reinsurance (Tables) </ShortName> |
| | | <MenuCategory> Tables </MenuCategory> |
| | | <ParentRole> http://imetrix.edgar-online.com/taxonomy/role/NotesToFinancialStatementsReinsuranceTextBlock </ParentRole> |
| | | <Position> 33 </Position> |
| | | </Report> |
| | <Report instance="ck0000839759-20181231.xml"> |
| | | <IsDefault> false </IsDefault> |
| | | <HasEmbeddedReports> false </HasEmbeddedReports> |
| | | <HtmlFileName> R34.htm </HtmlFileName> |
| | | <LongName> 1035 - Disclosure - Deferred Policy Acquisition and Sales Inducement Costs (Tables) </LongName> |
| | | <ReportType> Sheet </ReportType> |
| | | <Role> http://imetrix.edgar-online.com/taxonomy/role/NotesToFinancialStatementsDeferredPolicyAcquisitionCostsAndSalesInducementCostsDisclosureTextBlockTables </Role> |
| | | <ShortName> Deferred Policy Acquisition and Sales Inducement Costs (Tables) </ShortName> |
| | | <MenuCategory> Tables </MenuCategory> |
| | | <ParentRole> http://imetrix.edgar-online.com/taxonomy/role/NotesToFinancialStatementsDeferredPolicyAcquisitionCostsAndSalesInducementCostsDisclosureTextBlock </ParentRole> |
| | | <Position> 34 </Position> |
| | | </Report> |
| | <Report instance="ck0000839759-20181231.xml"> |
| | | <IsDefault> false </IsDefault> |
| | | <HasEmbeddedReports> false </HasEmbeddedReports> |
| | | <HtmlFileName> R35.htm </HtmlFileName> |
| | | <LongName> 1036 - Disclosure - Income Taxes (Tables) </LongName> |
| | | <ReportType> Sheet </ReportType> |
| | | <Role> http://imetrix.edgar-online.com/taxonomy/role/NotesToFinancialStatementsIncomeTaxDisclosureTextBlockTables </Role> |
| | | <ShortName> Income Taxes (Tables) </ShortName> |
| | | <MenuCategory> Tables </MenuCategory> |
| | | <ParentRole> http://imetrix.edgar-online.com/taxonomy/role/NotesToFinancialStatementsIncomeTaxDisclosureTextBlock </ParentRole> |
| | | <Position> 35 </Position> |
| | | </Report> |
| | <Report instance="ck0000839759-20181231.xml"> |
| | | <IsDefault> false </IsDefault> |
| | | <HasEmbeddedReports> false </HasEmbeddedReports> |
| | | <HtmlFileName> R36.htm </HtmlFileName> |
| | | <LongName> 1037 - Disclosure - Other Comprehensive Income (Tables) </LongName> |
| | | <ReportType> Sheet </ReportType> |
| | | <Role> http://imetrix.edgar-online.com/taxonomy/role/NotesToFinancialStatementsComprehensiveIncomeNoteTextBlockTables </Role> |
| | | <ShortName> Other Comprehensive Income (Tables) </ShortName> |
| | | <MenuCategory> Tables </MenuCategory> |
| | | <ParentRole> http://imetrix.edgar-online.com/taxonomy/role/NotesToFinancialStatementsComprehensiveIncomeNoteTextBlock </ParentRole> |
| | | <Position> 36 </Position> |
| | | </Report> |
| | <Report instance="ck0000839759-20181231.xml"> |
| | | <IsDefault> false </IsDefault> |
| | | <HasEmbeddedReports> false </HasEmbeddedReports> |
| | | <HtmlFileName> R37.htm </HtmlFileName> |
| | | <LongName> 1038 - Disclosure - General - Additional Information (Detail) </LongName> |
| | | <ReportType> Sheet </ReportType> |
| | | <Role> http://imetrix.edgar-online.com/taxonomy/role/DisclosureGeneralAdditionalInformation </Role> |
| | | <ShortName> General - Additional Information (Detail) </ShortName> |
| | | <MenuCategory> Details </MenuCategory> |
| | | <Position> 37 </Position> |
| | | </Report> |
| | <Report instance="ck0000839759-20181231.xml"> |
| | | <IsDefault> false </IsDefault> |
| | | <HasEmbeddedReports> false </HasEmbeddedReports> |
| | | <HtmlFileName> R38.htm </HtmlFileName> |
| | | <LongName> 1039 - Disclosure - Summary of Premiums and Contract Charges by Product (Detail) </LongName> |
| | | <ReportType> Sheet </ReportType> |
| | | <Role> http://imetrix.edgar-online.com/taxonomy/role/DisclosureSummaryOfPremiumsAndContractChargesByProduct </Role> |
| | | <ShortName> Summary of Premiums and Contract Charges by Product (Detail) </ShortName> |
| | | <MenuCategory> Details </MenuCategory> |
| | | <Position> 38 </Position> |
| | | </Report> |
| | <Report instance="ck0000839759-20181231.xml"> |
| | | <IsDefault> false </IsDefault> |
| | | <HasEmbeddedReports> false </HasEmbeddedReports> |
| | | <HtmlFileName> R39.htm </HtmlFileName> |
| | | <LongName> 1040 - Disclosure - Summary of Significant Accounting Policies - Additional Information (Detail) </LongName> |
| | | <ReportType> Sheet </ReportType> |
| | | <Role> http://imetrix.edgar-online.com/taxonomy/role/DisclosureSummaryOfSignificantAccountingPoliciesAdditionalInformation </Role> |
| | | <ShortName> Summary of Significant Accounting Policies - Additional Information (Detail) </ShortName> |
| | | <MenuCategory> Details </MenuCategory> |
| | | <Position> 39 </Position> |
| | | </Report> |
| | <Report instance="ck0000839759-20181231.xml"> |
| | | <IsDefault> false </IsDefault> |
| | | <HasEmbeddedReports> false </HasEmbeddedReports> |
| | | <HtmlFileName> R40.htm </HtmlFileName> |
| | | <LongName> 1041 - Disclosure - Supplemental Cash Flow Information - Additional Information (Detail) </LongName> |
| | | <ReportType> Sheet </ReportType> |
| | | <Role> http://imetrix.edgar-online.com/taxonomy/role/DisclosureSupplementalCashFlowInformationAdditionalInformation </Role> |
| | | <ShortName> Supplemental Cash Flow Information - Additional Information (Detail) </ShortName> |
| | | <MenuCategory> Details </MenuCategory> |
| | | <Position> 40 </Position> |
| | | </Report> |
| | <Report instance="ck0000839759-20181231.xml"> |
| | | <IsDefault> false </IsDefault> |
| | | <HasEmbeddedReports> false </HasEmbeddedReports> |
| | | <HtmlFileName> R41.htm </HtmlFileName> |
| | | <LongName> 1042 - Disclosure - Schedule of Supplemental Cash Flow Information (Detail) </LongName> |
| | | <ReportType> Sheet </ReportType> |
| | | <Role> http://imetrix.edgar-online.com/taxonomy/role/DisclosureScheduleOfSupplementalCashFlowInformation </Role> |
| | | <ShortName> Schedule of Supplemental Cash Flow Information (Detail) </ShortName> |
| | | <MenuCategory> Details </MenuCategory> |
| | | <Position> 41 </Position> |
| | | </Report> |
| | <Report instance="ck0000839759-20181231.xml"> |
| | | <IsDefault> false </IsDefault> |
| | | <HasEmbeddedReports> false </HasEmbeddedReports> |
| | | <HtmlFileName> R42.htm </HtmlFileName> |
| | | <LongName> 1043 - Disclosure - Related Party Transactions - Additional Information (Detail) </LongName> |
| | | <ReportType> Sheet </ReportType> |
| | | <Role> http://imetrix.edgar-online.com/taxonomy/role/DisclosureRelatedPartyTransactionsAdditionalInformation </Role> |
| | | <ShortName> Related Party Transactions - Additional Information (Detail) </ShortName> |
| | | <MenuCategory> Details </MenuCategory> |
| | | <Position> 42 </Position> |
| | | </Report> |
| | <Report instance="ck0000839759-20181231.xml"> |
| | | <IsDefault> false </IsDefault> |
| | | <HasEmbeddedReports> false </HasEmbeddedReports> |
| | | <HtmlFileName> R43.htm </HtmlFileName> |
| | | <LongName> 1044 - Disclosure - Schedule for Fixed Income Securities at Amortized Cost, Gross Unrealized Gains and Losses and Fair Value (Detail) </LongName> |
| | | <ReportType> Sheet </ReportType> |
| | | <Role> http://imetrix.edgar-online.com/taxonomy/role/DisclosureScheduleForFixedIncomeSecuritiesAtAmortizedCostGrossUnrealizedGainsAndLossesAndFairValue </Role> |
| | | <ShortName> Schedule for Fixed Income Securities at Amortized Cost, Gross Unrealized Gains and Losses and Fair Value (Detail) </ShortName> |
| | | <MenuCategory> Details </MenuCategory> |
| | | <Position> 43 </Position> |
| | | </Report> |
| | <Report instance="ck0000839759-20181231.xml"> |
| | | <IsDefault> false </IsDefault> |
| | | <HasEmbeddedReports> false </HasEmbeddedReports> |
| | | <HtmlFileName> R44.htm </HtmlFileName> |
| | | <LongName> 1045 - Disclosure - Schedule for Fixed Income Securities Based on Contractual Maturities (Detail) </LongName> |
| | | <ReportType> Sheet </ReportType> |
| | | <Role> http://imetrix.edgar-online.com/taxonomy/role/DisclosureScheduleForFixedIncomeSecuritiesBasedOnContractualMaturities </Role> |
| | | <ShortName> Schedule for Fixed Income Securities Based on Contractual Maturities (Detail) </ShortName> |
| | | <MenuCategory> Details </MenuCategory> |
| | | <Position> 44 </Position> |
| | | </Report> |
| | <Report instance="ck0000839759-20181231.xml"> |
| | | <IsDefault> false </IsDefault> |
| | | <HasEmbeddedReports> false </HasEmbeddedReports> |
| | | <HtmlFileName> R45.htm </HtmlFileName> |
| | | <LongName> 1046 - Disclosure - Schedule of Net Investment Income (Detail) </LongName> |
| | | <ReportType> Sheet </ReportType> |
| | | <Role> http://imetrix.edgar-online.com/taxonomy/role/DisclosureScheduleOfNetInvestmentIncome </Role> |
| | | <ShortName> Schedule of Net Investment Income (Detail) </ShortName> |
| | | <MenuCategory> Details </MenuCategory> |
| | | <Position> 45 </Position> |
| | | </Report> |
| | <Report instance="ck0000839759-20181231.xml"> |
| | | <IsDefault> false </IsDefault> |
| | | <HasEmbeddedReports> false </HasEmbeddedReports> |
| | | <HtmlFileName> R46.htm </HtmlFileName> |
| | | <LongName> 1047 - Disclosure - Schedule of Net Investment Income (Parenthetical) (Detail) </LongName> |
| | | <ReportType> Sheet </ReportType> |
| | | <Role> http://imetrix.edgar-online.com/taxonomy/role/DisclosureScheduleOfNetInvestmentIncomeParenthetical </Role> |
| | | <ShortName> Schedule of Net Investment Income (Parenthetical) (Detail) </ShortName> |
| | | <MenuCategory> Details </MenuCategory> |
| | | <Position> 46 </Position> |
| | | </Report> |
| | <Report instance="ck0000839759-20181231.xml"> |
| | | <IsDefault> false </IsDefault> |
| | | <HasEmbeddedReports> false </HasEmbeddedReports> |
| | | <HtmlFileName> R47.htm </HtmlFileName> |
| | | <LongName> 1048 - Disclosure - Schedule of Realized Capital Gains (Losses) by Asset Type (Detail) </LongName> |
| | | <ReportType> Sheet </ReportType> |
| | | <Role> http://imetrix.edgar-online.com/taxonomy/role/DisclosureScheduleOfRealizedCapitalGainsLossesByAssetType </Role> |
| | | <ShortName> Schedule of Realized Capital Gains (Losses) by Asset Type (Detail) </ShortName> |
| | | <MenuCategory> Details </MenuCategory> |
| | | <Position> 47 </Position> |
| | | </Report> |
| | <Report instance="ck0000839759-20181231.xml"> |
| | | <IsDefault> false </IsDefault> |
| | | <HasEmbeddedReports> false </HasEmbeddedReports> |
| | | <HtmlFileName> R48.htm </HtmlFileName> |
| | | <LongName> 1049 - Disclosure - Schedule of Realized Capital Gains (Losses) by Transaction Type (Detail) </LongName> |
| | | <ReportType> Sheet </ReportType> |
| | | <Role> http://imetrix.edgar-online.com/taxonomy/role/DisclosureScheduleOfRealizedCapitalGainsLossesByTransactionType </Role> |
| | | <ShortName> Schedule of Realized Capital Gains (Losses) by Transaction Type (Detail) </ShortName> |
| | | <MenuCategory> Details </MenuCategory> |
| | | <Position> 48 </Position> |
| | | </Report> |
| | <Report instance="ck0000839759-20181231.xml"> |
| | | <IsDefault> false </IsDefault> |
| | | <HasEmbeddedReports> false </HasEmbeddedReports> |
| | | <HtmlFileName> R49.htm </HtmlFileName> |
| | | <LongName> 1050 - Disclosure - Investments - Additional Information (Detail) </LongName> |
| | | <ReportType> Sheet </ReportType> |
| | | <Role> http://imetrix.edgar-online.com/taxonomy/role/DisclosureInvestmentsAdditionalInformation </Role> |
| | | <ShortName> Investments - Additional Information (Detail) </ShortName> |
| | | <MenuCategory> Details </MenuCategory> |
| | | <Position> 49 </Position> |
| | | </Report> |
| | <Report instance="ck0000839759-20181231.xml"> |
| | | <IsDefault> false </IsDefault> |
| | | <HasEmbeddedReports> false </HasEmbeddedReports> |
| | | <HtmlFileName> R50.htm </HtmlFileName> |
| | | <LongName> 1051 - Disclosure - Schedule of Net Pre-Tax Appreciation (Decline) of Equity Securities and Limited Partnership Interests Carried at Fair Value Recognized in Net Income (Detail) </LongName> |
| | | <ReportType> Sheet </ReportType> |
| | | <Role> http://imetrix.edgar-online.com/taxonomy/role/DisclosureScheduleOfNetPreTaxAppreciationDeclineOfEquitySecuritiesAndLimitedPartnershipInterestsCarriedAtFairValueRecognizedInNetIncome </Role> |
| | | <ShortName> Schedule of Net Pre-Tax Appreciation (Decline) of Equity Securities and Limited Partnership Interests Carried at Fair Value Recognized in Net Income (Detail) </ShortName> |
| | | <MenuCategory> Details </MenuCategory> |
| | | <Position> 50 </Position> |
| | | </Report> |
| | <Report instance="ck0000839759-20181231.xml"> |
| | | <IsDefault> false </IsDefault> |
| | | <HasEmbeddedReports> false </HasEmbeddedReports> |
| | | <HtmlFileName> R51.htm </HtmlFileName> |
| | | <LongName> 1052 - Disclosure - Schedule of Other-Than-Temporary Impairment Losses by Asset Type (Detail) </LongName> |
| | | <ReportType> Sheet </ReportType> |
| | | <Role> http://imetrix.edgar-online.com/taxonomy/role/DisclosureScheduleOfOtherThanTemporaryImpairmentLossesByAssetType </Role> |
| | | <ShortName> Schedule of Other-Than-Temporary Impairment Losses by Asset Type (Detail) </ShortName> |
| | | <MenuCategory> Details </MenuCategory> |
| | | <Position> 51 </Position> |
| | | </Report> |
| | <Report instance="ck0000839759-20181231.xml"> |
| | | <IsDefault> false </IsDefault> |
| | | <HasEmbeddedReports> false </HasEmbeddedReports> |
| | | <HtmlFileName> R52.htm </HtmlFileName> |
| | | <LongName> 1053 - Disclosure - Schedule of Other-Than-Temporary Impairment Losses on Fixed Income Securities included in Accumulated Other Comprehensive Income (Detail) </LongName> |
| | | <ReportType> Sheet </ReportType> |
| | | <Role> http://imetrix.edgar-online.com/taxonomy/role/DisclosureScheduleOfOtherThanTemporaryImpairmentLossesOnFixedIncomeSecuritiesIncludedInAccumulatedOtherComprehensiveIncome </Role> |
| | | <ShortName> Schedule of Other-Than-Temporary Impairment Losses on Fixed Income Securities included in Accumulated Other Comprehensive Income (Detail) </ShortName> |
| | | <MenuCategory> Details </MenuCategory> |
| | | <Position> 52 </Position> |
| | | </Report> |
| | <Report instance="ck0000839759-20181231.xml"> |
| | | <IsDefault> false </IsDefault> |
| | | <HasEmbeddedReports> false </HasEmbeddedReports> |
| | | <HtmlFileName> R53.htm </HtmlFileName> |
| | | <LongName> 1054 - Disclosure - Schedule of Rollforwards of Cumulative Credit Losses Recognized in Earnings for Fixed Income Securities Held (Detail) </LongName> |
| | | <ReportType> Sheet </ReportType> |
| | | <Role> http://imetrix.edgar-online.com/taxonomy/role/DisclosureScheduleOfRollforwardsOfCumulativeCreditLossesRecognizedInEarningsForFixedIncomeSecuritiesHeld </Role> |
| | | <ShortName> Schedule of Rollforwards of Cumulative Credit Losses Recognized in Earnings for Fixed Income Securities Held (Detail) </ShortName> |
| | | <MenuCategory> Details </MenuCategory> |
| | | <Position> 53 </Position> |
| | | </Report> |
| | <Report instance="ck0000839759-20181231.xml"> |
| | | <IsDefault> false </IsDefault> |
| | | <HasEmbeddedReports> false </HasEmbeddedReports> |
| | | <HtmlFileName> R54.htm </HtmlFileName> |
| | | <LongName> 1055 - Disclosure - Schedule of Unrealized Net Capital Gains and Losses (Detail) </LongName> |
| | | <ReportType> Sheet </ReportType> |
| | | <Role> http://imetrix.edgar-online.com/taxonomy/role/DisclosureScheduleOfUnrealizedNetCapitalGainsAndLosses </Role> |
| | | <ShortName> Schedule of Unrealized Net Capital Gains and Losses (Detail) </ShortName> |
| | | <MenuCategory> Details </MenuCategory> |
| | | <Position> 54 </Position> |
| | | </Report> |
| | <Report instance="ck0000839759-20181231.xml"> |
| | | <IsDefault> false </IsDefault> |
| | | <HasEmbeddedReports> false </HasEmbeddedReports> |
| | | <HtmlFileName> R55.htm </HtmlFileName> |
| | | <LongName> 1056 - Disclosure - Schedule of Change in Unrealized net Capital Gains and Losses (Detail) </LongName> |
| | | <ReportType> Sheet </ReportType> |
| | | <Role> http://imetrix.edgar-online.com/taxonomy/role/DisclosureScheduleOfChangeInUnrealizedNetCapitalGainsAndLosses </Role> |
| | | <ShortName> Schedule of Change in Unrealized net Capital Gains and Losses (Detail) </ShortName> |
| | | <MenuCategory> Details </MenuCategory> |
| | | <Position> 55 </Position> |
| | | </Report> |
| | <Report instance="ck0000839759-20181231.xml"> |
| | | <IsDefault> false </IsDefault> |
| | | <HasEmbeddedReports> false </HasEmbeddedReports> |
| | | <HtmlFileName> R56.htm </HtmlFileName> |
| | | <LongName> 1057 - Disclosure - Schedule of Change in Unrealized net Capital Gains and Losses (Parenthetical) (Detail) </LongName> |
| | | <ReportType> Sheet </ReportType> |
| | | <Role> http://imetrix.edgar-online.com/taxonomy/role/DisclosureScheduleOfChangeInUnrealizedNetCapitalGainsAndLossesParenthetical </Role> |
| | | <ShortName> Schedule of Change in Unrealized net Capital Gains and Losses (Parenthetical) (Detail) </ShortName> |
| | | <MenuCategory> Details </MenuCategory> |
| | | <Position> 56 </Position> |
| | | </Report> |
| | <Report instance="ck0000839759-20181231.xml"> |
| | | <IsDefault> false </IsDefault> |
| | | <HasEmbeddedReports> false </HasEmbeddedReports> |
| | | <HtmlFileName> R57.htm </HtmlFileName> |
| | | <LongName> 1058 - Disclosure - Summary of Gross Unrealized Losses and Fair Value of Fixed Income and Equity Securities by Length of Time (Detail) </LongName> |
| | | <ReportType> Sheet </ReportType> |
| | | <Role> http://imetrix.edgar-online.com/taxonomy/role/DisclosureSummaryOfGrossUnrealizedLossesAndFairValueOfFixedIncomeAndEquitySecuritiesByLengthOfTime </Role> |
| | | <ShortName> Summary of Gross Unrealized Losses and Fair Value of Fixed Income and Equity Securities by Length of Time (Detail) </ShortName> |
| | | <MenuCategory> Details </MenuCategory> |
| | | <Position> 57 </Position> |
| | | </Report> |
| | <Report instance="ck0000839759-20181231.xml"> |
| | | <IsDefault> false </IsDefault> |
| | | <HasEmbeddedReports> false </HasEmbeddedReports> |
| | | <HtmlFileName> R58.htm </HtmlFileName> |
| | | <LongName> 1059 - Disclosure - Schedule of Commercial Mortgage Loans by Geographic Distribution (Detail) </LongName> |
| | | <ReportType> Sheet </ReportType> |
| | | <Role> http://imetrix.edgar-online.com/taxonomy/role/DisclosureScheduleOfCommercialMortgageLoansByGeographicDistribution </Role> |
| | | <ShortName> Schedule of Commercial Mortgage Loans by Geographic Distribution (Detail) </ShortName> |
| | | <MenuCategory> Details </MenuCategory> |
| | | <Position> 58 </Position> |
| | | </Report> |
| | <Report instance="ck0000839759-20181231.xml"> |
| | | <IsDefault> false </IsDefault> |
| | | <HasEmbeddedReports> false </HasEmbeddedReports> |
| | | <HtmlFileName> R59.htm </HtmlFileName> |
| | | <LongName> 1060 - Disclosure - Schedule of Types of Properties Collateralizing Commercial Mortgage Loans (Detail) </LongName> |
| | | <ReportType> Sheet </ReportType> |
| | | <Role> http://imetrix.edgar-online.com/taxonomy/role/DisclosureScheduleOfTypesOfPropertiesCollateralizingCommercialMortgageLoans </Role> |
| | | <ShortName> Schedule of Types of Properties Collateralizing Commercial Mortgage Loans (Detail) </ShortName> |
| | | <MenuCategory> Details </MenuCategory> |
| | | <Position> 59 </Position> |
| | | </Report> |
| | <Report instance="ck0000839759-20181231.xml"> |
| | | <IsDefault> false </IsDefault> |
| | | <HasEmbeddedReports> false </HasEmbeddedReports> |
| | | <HtmlFileName> R60.htm </HtmlFileName> |
| | | <LongName> 1061 - Disclosure - Schedule of Contractual Maturities of Mortgage Loans (Detail) </LongName> |
| | | <ReportType> Sheet </ReportType> |
| | | <Role> http://imetrix.edgar-online.com/taxonomy/role/DisclosureScheduleOfContractualMaturitiesOfMortgageLoans </Role> |
| | | <ShortName> Schedule of Contractual Maturities of Mortgage Loans (Detail) </ShortName> |
| | | <MenuCategory> Details </MenuCategory> |
| | | <Position> 60 </Position> |
| | | </Report> |
| | <Report instance="ck0000839759-20181231.xml"> |
| | | <IsDefault> false </IsDefault> |
| | | <HasEmbeddedReports> false </HasEmbeddedReports> |
| | | <HtmlFileName> R61.htm </HtmlFileName> |
| | | <LongName> 1062 - Disclosure - Summary of Carrying Value of Non-Impaired Mortgage Loans by Debt Service Coverage Ration Distribution (Detail) </LongName> |
| | | <ReportType> Sheet </ReportType> |
| | | <Role> http://imetrix.edgar-online.com/taxonomy/role/DisclosureSummaryOfCarryingValueOfNonImpairedMortgageLoansByDebtServiceCoverageRationDistribution </Role> |
| | | <ShortName> Summary of Carrying Value of Non-Impaired Mortgage Loans by Debt Service Coverage Ration Distribution (Detail) </ShortName> |
| | | <MenuCategory> Details </MenuCategory> |
| | | <Position> 61 </Position> |
| | | </Report> |
| | <Report instance="ck0000839759-20181231.xml"> |
| | | <IsDefault> false </IsDefault> |
| | | <HasEmbeddedReports> false </HasEmbeddedReports> |
| | | <HtmlFileName> R62.htm </HtmlFileName> |
| | | <LongName> 1063 - Disclosure - Schedule of Municipal Bonds Held For Investment by Geographic Distribution (Detail) </LongName> |
| | | <ReportType> Sheet </ReportType> |
| | | <Role> http://imetrix.edgar-online.com/taxonomy/role/DisclosureScheduleOfMunicipalBondsHeldForInvestmentByGeographicDistribution </Role> |
| | | <ShortName> Schedule of Municipal Bonds Held For Investment by Geographic Distribution (Detail) </ShortName> |
| | | <MenuCategory> Details </MenuCategory> |
| | | <Position> 62 </Position> |
| | | </Report> |
| | <Report instance="ck0000839759-20181231.xml"> |
| | | <IsDefault> false </IsDefault> |
| | | <HasEmbeddedReports> false </HasEmbeddedReports> |
| | | <HtmlFileName> R63.htm </HtmlFileName> |
| | | <LongName> 1064 - Disclosure - Fair Value of Assets and Liabilities - Additional Information (Detail) </LongName> |
| | | <ReportType> Sheet </ReportType> |
| | | <Role> http://imetrix.edgar-online.com/taxonomy/role/DisclosureFairValueOfAssetsAndLiabilitiesAdditionalInformation </Role> |
| | | <ShortName> Fair Value of Assets and Liabilities - Additional Information (Detail) </ShortName> |
| | | <MenuCategory> Details </MenuCategory> |
| | | <Position> 63 </Position> |
| | | </Report> |
| | <Report instance="ck0000839759-20181231.xml"> |
| | | <IsDefault> false </IsDefault> |
| | | <HasEmbeddedReports> false </HasEmbeddedReports> |
| | | <HtmlFileName> R64.htm </HtmlFileName> |
| | | <LongName> 1065 - Disclosure - Summary of Assets and Liabilities Measured at Fair Value on Recurring and Non-Recurring Basis (Detail) </LongName> |
| | | <ReportType> Sheet </ReportType> |
| | | <Role> http://imetrix.edgar-online.com/taxonomy/role/DisclosureSummaryOfAssetsAndLiabilitiesMeasuredAtFairValueOnRecurringAndNonRecurringBasis </Role> |
| | | <ShortName> Summary of Assets and Liabilities Measured at Fair Value on Recurring and Non-Recurring Basis (Detail) </ShortName> |
| | | <MenuCategory> Details </MenuCategory> |
| | | <Position> 64 </Position> |
| | | </Report> |
| | <Report instance="ck0000839759-20181231.xml"> |
| | | <IsDefault> false </IsDefault> |
| | | <HasEmbeddedReports> false </HasEmbeddedReports> |
| | | <HtmlFileName> R65.htm </HtmlFileName> |
| | | <LongName> 1066 - Disclosure - Summary of Quantitative Information About Significant Unobservable Inputs Used in Level Three Fair Value Measurements (Detail) </LongName> |
| | | <ReportType> Sheet </ReportType> |
| | | <Role> http://imetrix.edgar-online.com/taxonomy/role/DisclosureSummaryOfQuantitativeInformationAboutSignificantUnobservableInputsUsedInLevelThreeFairValueMeasurements </Role> |
| | | <ShortName> Summary of Quantitative Information About Significant Unobservable Inputs Used in Level Three Fair Value Measurements (Detail) </ShortName> |
| | | <MenuCategory> Details </MenuCategory> |
| | | <Position> 65 </Position> |
| | | </Report> |
| | <Report instance="ck0000839759-20181231.xml"> |
| | | <IsDefault> false </IsDefault> |
| | | <HasEmbeddedReports> false </HasEmbeddedReports> |
| | | <HtmlFileName> R66.htm </HtmlFileName> |
| | | <LongName> 1067 - Disclosure - Schedule of Rollforward of Level 3 Assets and Liabilities Held at Fair Value on Recurring Basis (Detail) </LongName> |
| | | <ReportType> Sheet </ReportType> |
| | | <Role> http://imetrix.edgar-online.com/taxonomy/role/DisclosureScheduleOfRollforwardOfLevel3AssetsAndLiabilitiesHeldAtFairValueOnRecurringBasis </Role> |
| | | <ShortName> Schedule of Rollforward of Level 3 Assets and Liabilities Held at Fair Value on Recurring Basis (Detail) </ShortName> |
| | | <MenuCategory> Details </MenuCategory> |
| | | <Position> 66 </Position> |
| | | </Report> |
| | <Report instance="ck0000839759-20181231.xml"> |
| | | <IsDefault> false </IsDefault> |
| | | <HasEmbeddedReports> false </HasEmbeddedReports> |
| | | <HtmlFileName> R67.htm </HtmlFileName> |
| | | <LongName> 1068 - Disclosure - Schedule of Rollforward of Level 3 Assets and Liabilities Held at Fair Value on Recurring Basis (Parenthetical) (Detail) </LongName> |
| | | <ReportType> Sheet </ReportType> |
| | | <Role> http://imetrix.edgar-online.com/taxonomy/role/DisclosureScheduleOfRollforwardOfLevel3AssetsAndLiabilitiesHeldAtFairValueOnRecurringBasisParenthetical </Role> |
| | | <ShortName> Schedule of Rollforward of Level 3 Assets and Liabilities Held at Fair Value on Recurring Basis (Parenthetical) (Detail) </ShortName> |
| | | <MenuCategory> Details </MenuCategory> |
| | | <Position> 67 </Position> |
| | | </Report> |
| | <Report instance="ck0000839759-20181231.xml"> |
| | | <IsDefault> false </IsDefault> |
| | | <HasEmbeddedReports> false </HasEmbeddedReports> |
| | | <HtmlFileName> R68.htm </HtmlFileName> |
| | | <LongName> 1069 - Disclosure - Schedule of Change in Unrealized Gains and Losses Included in Net Income for Level Three Assets and Liabilities Held (Detail) </LongName> |
| | | <ReportType> Sheet </ReportType> |
| | | <Role> http://imetrix.edgar-online.com/taxonomy/role/DisclosureScheduleOfChangeInUnrealizedGainsAndLossesIncludedInNetIncomeForLevelThreeAssetsAndLiabilitiesHeld </Role> |
| | | <ShortName> Schedule of Change in Unrealized Gains and Losses Included in Net Income for Level Three Assets and Liabilities Held (Detail) </ShortName> |
| | | <MenuCategory> Details </MenuCategory> |
| | | <Position> 68 </Position> |
| | | </Report> |
| | <Report instance="ck0000839759-20181231.xml"> |
| | | <IsDefault> false </IsDefault> |
| | | <HasEmbeddedReports> false </HasEmbeddedReports> |
| | | <HtmlFileName> R69.htm </HtmlFileName> |
| | | <LongName> 1070 - Disclosure - Schedule of Carrying Values and Fair Value Estimates of Financial Instruments not Carried at Fair Value (Detail) </LongName> |
| | | <ReportType> Sheet </ReportType> |
| | | <Role> http://imetrix.edgar-online.com/taxonomy/role/DisclosureScheduleOfCarryingValuesAndFairValueEstimatesOfFinancialInstrumentsNotCarriedAtFairValue </Role> |
| | | <ShortName> Schedule of Carrying Values and Fair Value Estimates of Financial Instruments not Carried at Fair Value (Detail) </ShortName> |
| | | <MenuCategory> Details </MenuCategory> |
| | | <Position> 69 </Position> |
| | | </Report> |
| | <Report instance="ck0000839759-20181231.xml"> |
| | | <IsDefault> false </IsDefault> |
| | | <HasEmbeddedReports> false </HasEmbeddedReports> |
| | | <HtmlFileName> R70.htm </HtmlFileName> |
| | | <LongName> 1071 - Disclosure - Summary of Volume and Fair Value Positions of Derivative Instruments and Reporting Location in Statement of Financial Position (Detail) </LongName> |
| | | <ReportType> Sheet </ReportType> |
| | | <Role> http://imetrix.edgar-online.com/taxonomy/role/DisclosureSummaryOfVolumeAndFairValuePositionsOfDerivativeInstrumentsAndReportingLocationInStatementOfFinancialPosition </Role> |
| | | <ShortName> Summary of Volume and Fair Value Positions of Derivative Instruments and Reporting Location in Statement of Financial Position (Detail) </ShortName> |
| | | <MenuCategory> Details </MenuCategory> |
| | | <Position> 70 </Position> |
| | | </Report> |
| | <Report instance="ck0000839759-20181231.xml"> |
| | | <IsDefault> false </IsDefault> |
| | | <HasEmbeddedReports> false </HasEmbeddedReports> |
| | | <HtmlFileName> R71.htm </HtmlFileName> |
| | | <LongName> 1072 - Disclosure - Schedule of Gross and Net Amount for Company's OTC Derivatives Subject to Enforceable Master Netting Arrangements (Detail) </LongName> |
| | | <ReportType> Sheet </ReportType> |
| | | <Role> http://imetrix.edgar-online.com/taxonomy/role/DisclosureScheduleOfGrossAndNetAmountForCompanysOTCDerivativesSubjectToEnforceableMasterNettingArrangements </Role> |
| | | <ShortName> Schedule of Gross and Net Amount for Company's OTC Derivatives Subject to Enforceable Master Netting Arrangements (Detail) </ShortName> |
| | | <MenuCategory> Details </MenuCategory> |
| | | <Position> 71 </Position> |
| | | </Report> |
| | <Report instance="ck0000839759-20181231.xml"> |
| | | <IsDefault> false </IsDefault> |
| | | <HasEmbeddedReports> false </HasEmbeddedReports> |
| | | <HtmlFileName> R72.htm </HtmlFileName> |
| | | <LongName> 1073 - Disclosure - Summary of Gains and Losses from Valuation and Settlements For Derivatives Not Designated As Hedges (Detail) </LongName> |
| | | <ReportType> Sheet </ReportType> |
| | | <Role> http://imetrix.edgar-online.com/taxonomy/role/DisclosureSummaryOfGainsAndLossesFromValuationAndSettlementsForDerivativesNotDesignatedAsHedges </Role> |
| | | <ShortName> Summary of Gains and Losses from Valuation and Settlements For Derivatives Not Designated As Hedges (Detail) </ShortName> |
| | | <MenuCategory> Details </MenuCategory> |
| | | <Position> 72 </Position> |
| | | </Report> |
| | <Report instance="ck0000839759-20181231.xml"> |
| | | <IsDefault> false </IsDefault> |
| | | <HasEmbeddedReports> false </HasEmbeddedReports> |
| | | <HtmlFileName> R73.htm </HtmlFileName> |
| | | <LongName> 1074 - Disclosure - Derivative Financial Instruments and Off-balance sheet Financial Instruments - Additional Information (Detail) </LongName> |
| | | <ReportType> Sheet </ReportType> |
| | | <Role> http://imetrix.edgar-online.com/taxonomy/role/DisclosureDerivativeFinancialInstrumentsAndOffbalanceSheetFinancialInstrumentsAdditionalInformation </Role> |
| | | <ShortName> Derivative Financial Instruments and Off-balance sheet Financial Instruments - Additional Information (Detail) </ShortName> |
| | | <MenuCategory> Details </MenuCategory> |
| | | <Position> 73 </Position> |
| | | </Report> |
| | <Report instance="ck0000839759-20181231.xml"> |
| | | <IsDefault> false </IsDefault> |
| | | <HasEmbeddedReports> false </HasEmbeddedReports> |
| | | <HtmlFileName> R74.htm </HtmlFileName> |
| | | <LongName> 1075 - Disclosure - Summary of Counterparty Credit Exposure by Counterparty Credit Rating (Detail) </LongName> |
| | | <ReportType> Sheet </ReportType> |
| | | <Role> http://imetrix.edgar-online.com/taxonomy/role/DisclosureSummaryOfCounterpartyCreditExposureByCounterpartyCreditRating </Role> |
| | | <ShortName> Summary of Counterparty Credit Exposure by Counterparty Credit Rating (Detail) </ShortName> |
| | | <MenuCategory> Details </MenuCategory> |
| | | <Position> 74 </Position> |
| | | </Report> |
| | <Report instance="ck0000839759-20181231.xml"> |
| | | <IsDefault> false </IsDefault> |
| | | <HasEmbeddedReports> false </HasEmbeddedReports> |
| | | <HtmlFileName> R75.htm </HtmlFileName> |
| | | <LongName> 1076 - Disclosure - Derivatives Financial Instruments and Off Balance Sheet Financial Instruments -Summary of Fair Value of Derivatives (Detail) </LongName> |
| | | <ReportType> Sheet </ReportType> |
| | | <Role> http://imetrix.edgar-online.com/taxonomy/role/DisclosureDerivativesFinancialInstrumentsAndOffBalanceSheetFinancialInstrumentsSummaryOfFairValueOfDerivatives </Role> |
| | | <ShortName> Derivatives Financial Instruments and Off Balance Sheet Financial Instruments -Summary of Fair Value of Derivatives (Detail) </ShortName> |
| | | <MenuCategory> Details </MenuCategory> |
| | | <Position> 75 </Position> |
| | | </Report> |
| | <Report instance="ck0000839759-20181231.xml"> |
| | | <IsDefault> false </IsDefault> |
| | | <HasEmbeddedReports> false </HasEmbeddedReports> |
| | | <HtmlFileName> R76.htm </HtmlFileName> |
| | | <LongName> 1077 - Disclosure - Derivatives Financial Instruments and Off Balance Sheet Financial Instruments - Schedule of Contractual Amounts of Off Balance Sheet Financial instruments (Detail) </LongName> |
| | | <ReportType> Sheet </ReportType> |
| | | <Role> http://imetrix.edgar-online.com/taxonomy/role/DisclosureDerivativesFinancialInstrumentsAndOffBalanceSheetFinancialInstrumentsScheduleOfContractualAmountsOfOffBalanceSheetFinancialInstruments </Role> |
| | | <ShortName> Derivatives Financial Instruments and Off Balance Sheet Financial Instruments - Schedule of Contractual Amounts of Off Balance Sheet Financial instruments (Detail) </ShortName> |
| | | <MenuCategory> Details </MenuCategory> |
| | | <Position> 76 </Position> |
| | | </Report> |
| | <Report instance="ck0000839759-20181231.xml"> |
| | | <IsDefault> false </IsDefault> |
| | | <HasEmbeddedReports> false </HasEmbeddedReports> |
| | | <HtmlFileName> R77.htm </HtmlFileName> |
| | | <LongName> 1078 - Disclosure - Schedule of Reserve for Life-Contingent Contract Benefits (Detail) </LongName> |
| | | <ReportType> Sheet </ReportType> |
| | | <Role> http://imetrix.edgar-online.com/taxonomy/role/DisclosureScheduleOfReserveForLifeContingentContractBenefits </Role> |
| | | <ShortName> Schedule of Reserve for Life-Contingent Contract Benefits (Detail) </ShortName> |
| | | <MenuCategory> Details </MenuCategory> |
| | | <Position> 77 </Position> |
| | | </Report> |
| | <Report instance="ck0000839759-20181231.xml"> |
| | | <IsDefault> false </IsDefault> |
| | | <HasEmbeddedReports> false </HasEmbeddedReports> |
| | | <HtmlFileName> R78.htm </HtmlFileName> |
| | | <LongName> 1079 - Disclosure - Schedule of Key Assumptions Used In Calculation Reserve for Life-Contingent Contract Benefits (Detail) </LongName> |
| | | <ReportType> Sheet </ReportType> |
| | | <Role> http://imetrix.edgar-online.com/taxonomy/role/DisclosureScheduleOfKeyAssumptionsUsedInCalculationReserveForLifeContingentContractBenefits </Role> |
| | | <ShortName> Schedule of Key Assumptions Used In Calculation Reserve for Life-Contingent Contract Benefits (Detail) </ShortName> |
| | | <MenuCategory> Details </MenuCategory> |
| | | <Position> 78 </Position> |
| | | </Report> |
| | <Report instance="ck0000839759-20181231.xml"> |
| | | <IsDefault> false </IsDefault> |
| | | <HasEmbeddedReports> false </HasEmbeddedReports> |
| | | <HtmlFileName> R79.htm </HtmlFileName> |
| | | <LongName> 1080 - Disclosure - Reserve for Life-Contingent Contract Benefits and Contractholder Funds - Additional Information (Detail) </LongName> |
| | | <ReportType> Sheet </ReportType> |
| | | <Role> http://imetrix.edgar-online.com/taxonomy/role/DisclosureReserveForLifeContingentContractBenefitsAndContractholderFundsAdditionalInformation </Role> |
| | | <ShortName> Reserve for Life-Contingent Contract Benefits and Contractholder Funds - Additional Information (Detail) </ShortName> |
| | | <MenuCategory> Details </MenuCategory> |
| | | <Position> 79 </Position> |
| | | </Report> |
| | <Report instance="ck0000839759-20181231.xml"> |
| | | <IsDefault> false </IsDefault> |
| | | <HasEmbeddedReports> false </HasEmbeddedReports> |
| | | <HtmlFileName> R80.htm </HtmlFileName> |
| | | <LongName> 1081 - Disclosure - Schedule of Contractholder Funds (Detail) </LongName> |
| | | <ReportType> Sheet </ReportType> |
| | | <Role> http://imetrix.edgar-online.com/taxonomy/role/DisclosureScheduleOfContractholderFunds </Role> |
| | | <ShortName> Schedule of Contractholder Funds (Detail) </ShortName> |
| | | <MenuCategory> Details </MenuCategory> |
| | | <Position> 80 </Position> |
| | | </Report> |
| | <Report instance="ck0000839759-20181231.xml"> |
| | | <IsDefault> false </IsDefault> |
| | | <HasEmbeddedReports> false </HasEmbeddedReports> |
| | | <HtmlFileName> R81.htm </HtmlFileName> |
| | | <LongName> 1082 - Disclosure - Schedule of Contract Provisions Related to Contractholder Funds (Detail) </LongName> |
| | | <ReportType> Sheet </ReportType> |
| | | <Role> http://imetrix.edgar-online.com/taxonomy/role/DisclosureScheduleOfContractProvisionsRelatedToContractholderFunds </Role> |
| | | <ShortName> Schedule of Contract Provisions Related to Contractholder Funds (Detail) </ShortName> |
| | | <MenuCategory> Details </MenuCategory> |
| | | <Position> 81 </Position> |
| | | </Report> |
| | <Report instance="ck0000839759-20181231.xml"> |
| | | <IsDefault> false </IsDefault> |
| | | <HasEmbeddedReports> false </HasEmbeddedReports> |
| | | <HtmlFileName> R82.htm </HtmlFileName> |
| | | <LongName> 1083 - Disclosure - Schedule of Contractholder Funds Activity (Detail) </LongName> |
| | | <ReportType> Sheet </ReportType> |
| | | <Role> http://imetrix.edgar-online.com/taxonomy/role/DisclosureScheduleOfContractholderFundsActivity </Role> |
| | | <ShortName> Schedule of Contractholder Funds Activity (Detail) </ShortName> |
| | | <MenuCategory> Details </MenuCategory> |
| | | <Position> 82 </Position> |
| | | </Report> |
| | <Report instance="ck0000839759-20181231.xml"> |
| | | <IsDefault> false </IsDefault> |
| | | <HasEmbeddedReports> false </HasEmbeddedReports> |
| | | <HtmlFileName> R83.htm </HtmlFileName> |
| | | <LongName> 1084 - Disclosure - Summary of Variable Annuity Contracts with Guarantees (Detail) </LongName> |
| | | <ReportType> Sheet </ReportType> |
| | | <Role> http://imetrix.edgar-online.com/taxonomy/role/DisclosureSummaryOfVariableAnnuityContractsWithGuarantees </Role> |
| | | <ShortName> Summary of Variable Annuity Contracts with Guarantees (Detail) </ShortName> |
| | | <MenuCategory> Details </MenuCategory> |
| | | <Position> 83 </Position> |
| | | </Report> |
| | <Report instance="ck0000839759-20181231.xml"> |
| | | <IsDefault> false </IsDefault> |
| | | <HasEmbeddedReports> false </HasEmbeddedReports> |
| | | <HtmlFileName> R84.htm </HtmlFileName> |
| | | <LongName> 1085 - Disclosure - Summary of Liabilities for Guarantees (Detail) </LongName> |
| | | <ReportType> Sheet </ReportType> |
| | | <Role> http://imetrix.edgar-online.com/taxonomy/role/DisclosureSummaryOfLiabilitiesForGuarantees </Role> |
| | | <ShortName> Summary of Liabilities for Guarantees (Detail) </ShortName> |
| | | <MenuCategory> Details </MenuCategory> |
| | | <Position> 84 </Position> |
| | | </Report> |
| | <Report instance="ck0000839759-20181231.xml"> |
| | | <IsDefault> false </IsDefault> |
| | | <HasEmbeddedReports> false </HasEmbeddedReports> |
| | | <HtmlFileName> R85.htm </HtmlFileName> |
| | | <LongName> 1086 - Disclosure - Summary of Liabilities for Guarantees (Parenthetical) (Detail) </LongName> |
| | | <ReportType> Sheet </ReportType> |
| | | <Role> http://imetrix.edgar-online.com/taxonomy/role/DisclosureSummaryOfLiabilitiesForGuaranteesParenthetical </Role> |
| | | <ShortName> Summary of Liabilities for Guarantees (Parenthetical) (Detail) </ShortName> |
| | | <MenuCategory> Details </MenuCategory> |
| | | <Position> 85 </Position> |
| | | </Report> |
| | <Report instance="ck0000839759-20181231.xml"> |
| | | <IsDefault> false </IsDefault> |
| | | <HasEmbeddedReports> false </HasEmbeddedReports> |
| | | <HtmlFileName> R86.htm </HtmlFileName> |
| | | <LongName> 1087 - Disclosure - Reinsurance - Additional Information (Detail) </LongName> |
| | | <ReportType> Sheet </ReportType> |
| | | <Role> http://imetrix.edgar-online.com/taxonomy/role/DisclosureReinsuranceAdditionalInformation </Role> |
| | | <ShortName> Reinsurance - Additional Information (Detail) </ShortName> |
| | | <MenuCategory> Details </MenuCategory> |
| | | <Position> 86 </Position> |
| | | </Report> |
| | <Report instance="ck0000839759-20181231.xml"> |
| | | <IsDefault> false </IsDefault> |
| | | <HasEmbeddedReports> false </HasEmbeddedReports> |
| | | <HtmlFileName> R87.htm </HtmlFileName> |
| | | <LongName> 1088 - Disclosure - Schedule of Effects of Reinsurance on Premiums and Contract Charges (Detail) </LongName> |
| | | <ReportType> Sheet </ReportType> |
| | | <Role> http://imetrix.edgar-online.com/taxonomy/role/DisclosureScheduleOfEffectsOfReinsuranceOnPremiumsAndContractCharges </Role> |
| | | <ShortName> Schedule of Effects of Reinsurance on Premiums and Contract Charges (Detail) </ShortName> |
| | | <MenuCategory> Details </MenuCategory> |
| | | <Position> 87 </Position> |
| | | </Report> |
| | <Report instance="ck0000839759-20181231.xml"> |
| | | <IsDefault> false </IsDefault> |
| | | <HasEmbeddedReports> false </HasEmbeddedReports> |
| | | <HtmlFileName> R88.htm </HtmlFileName> |
| | | <LongName> 1089 - Disclosure - Schedule of Effects of Reinsurance on Contract Benefits (Detail) </LongName> |
| | | <ReportType> Sheet </ReportType> |
| | | <Role> http://imetrix.edgar-online.com/taxonomy/role/DisclosureScheduleOfEffectsOfReinsuranceOnContractBenefits </Role> |
| | | <ShortName> Schedule of Effects of Reinsurance on Contract Benefits (Detail) </ShortName> |
| | | <MenuCategory> Details </MenuCategory> |
| | | <Position> 88 </Position> |
| | | </Report> |
| | <Report instance="ck0000839759-20181231.xml"> |
| | | <IsDefault> false </IsDefault> |
| | | <HasEmbeddedReports> false </HasEmbeddedReports> |
| | | <HtmlFileName> R89.htm </HtmlFileName> |
| | | <LongName> 1090 - Disclosure - Schedule of Effect of Reinsurance on Interest Credited to Contractholder Funds (Detail) </LongName> |
| | | <ReportType> Sheet </ReportType> |
| | | <Role> http://imetrix.edgar-online.com/taxonomy/role/DisclosureScheduleOfEffectOfReinsuranceOnInterestCreditedToContractholderFunds </Role> |
| | | <ShortName> Schedule of Effect of Reinsurance on Interest Credited to Contractholder Funds (Detail) </ShortName> |
| | | <MenuCategory> Details </MenuCategory> |
| | | <Position> 89 </Position> |
| | | </Report> |
| | <Report instance="ck0000839759-20181231.xml"> |
| | | <IsDefault> false </IsDefault> |
| | | <HasEmbeddedReports> false </HasEmbeddedReports> |
| | | <HtmlFileName> R90.htm </HtmlFileName> |
| | | <LongName> 1091 - Disclosure - Schedule of Deferred Policy Acquisition Costs (Detail) </LongName> |
| | | <ReportType> Sheet </ReportType> |
| | | <Role> http://imetrix.edgar-online.com/taxonomy/role/DisclosureScheduleOfDeferredPolicyAcquisitionCosts </Role> |
| | | <ShortName> Schedule of Deferred Policy Acquisition Costs (Detail) </ShortName> |
| | | <MenuCategory> Details </MenuCategory> |
| | | <Position> 90 </Position> |
| | | </Report> |
| | <Report instance="ck0000839759-20181231.xml"> |
| | | <IsDefault> false </IsDefault> |
| | | <HasEmbeddedReports> false </HasEmbeddedReports> |
| | | <HtmlFileName> R91.htm </HtmlFileName> |
| | | <LongName> 1092 - Disclosure - Schedule of Deferred Sales Inducement Activity (Detail) </LongName> |
| | | <ReportType> Sheet </ReportType> |
| | | <Role> http://imetrix.edgar-online.com/taxonomy/role/DisclosureScheduleOfDeferredSalesInducementActivity </Role> |
| | | <ShortName> Schedule of Deferred Sales Inducement Activity (Detail) </ShortName> |
| | | <MenuCategory> Details </MenuCategory> |
| | | <Position> 91 </Position> |
| | | </Report> |
| | <Report instance="ck0000839759-20181231.xml"> |
| | | <IsDefault> false </IsDefault> |
| | | <HasEmbeddedReports> false </HasEmbeddedReports> |
| | | <HtmlFileName> R92.htm </HtmlFileName> |
| | | <LongName> 1093 - Disclosure - Guarantees and Contingent Liabilities - Additional Information (Detail) </LongName> |
| | | <ReportType> Sheet </ReportType> |
| | | <Role> http://imetrix.edgar-online.com/taxonomy/role/DisclosureGuaranteesAndContingentLiabilitiesAdditionalInformation </Role> |
| | | <ShortName> Guarantees and Contingent Liabilities - Additional Information (Detail) </ShortName> |
| | | <MenuCategory> Details </MenuCategory> |
| | | <Position> 92 </Position> |
| | | </Report> |
| | <Report instance="ck0000839759-20181231.xml"> |
| | | <IsDefault> false </IsDefault> |
| | | <HasEmbeddedReports> false </HasEmbeddedReports> |
| | | <HtmlFileName> R93.htm </HtmlFileName> |
| | | <LongName> 1094 - Disclosure - Income Taxes - Additional Information (Detail) </LongName> |
| | | <ReportType> Sheet </ReportType> |
| | | <Role> http://imetrix.edgar-online.com/taxonomy/role/DisclosureIncomeTaxesAdditionalInformation </Role> |
| | | <ShortName> Income Taxes - Additional Information (Detail) </ShortName> |
| | | <MenuCategory> Details </MenuCategory> |
| | | <Position> 93 </Position> |
| | | </Report> |
| | <Report instance="ck0000839759-20181231.xml"> |
| | | <IsDefault> false </IsDefault> |
| | | <HasEmbeddedReports> false </HasEmbeddedReports> |
| | | <HtmlFileName> R94.htm </HtmlFileName> |
| | | <LongName> 1095 - Disclosure - Components of Deferred Income Tax Assets and Liabilities (Detail) </LongName> |
| | | <ReportType> Sheet </ReportType> |
| | | <Role> http://imetrix.edgar-online.com/taxonomy/role/DisclosureComponentsOfDeferredIncomeTaxAssetsAndLiabilities </Role> |
| | | <ShortName> Components of Deferred Income Tax Assets and Liabilities (Detail) </ShortName> |
| | | <MenuCategory> Details </MenuCategory> |
| | | <Position> 94 </Position> |
| | | </Report> |
| | <Report instance="ck0000839759-20181231.xml"> |
| | | <IsDefault> false </IsDefault> |
| | | <HasEmbeddedReports> false </HasEmbeddedReports> |
| | | <HtmlFileName> R95.htm </HtmlFileName> |
| | | <LongName> 1096 - Disclosure - Components of Income Tax Benefit Expense (Detail) </LongName> |
| | | <ReportType> Sheet </ReportType> |
| | | <Role> http://imetrix.edgar-online.com/taxonomy/role/DisclosureComponentsOfIncomeTaxBenefitExpense </Role> |
| | | <ShortName> Components of Income Tax Benefit Expense (Detail) </ShortName> |
| | | <MenuCategory> Details </MenuCategory> |
| | | <Position> 95 </Position> |
| | | </Report> |
| | <Report instance="ck0000839759-20181231.xml"> |
| | | <IsDefault> false </IsDefault> |
| | | <HasEmbeddedReports> false </HasEmbeddedReports> |
| | | <HtmlFileName> R96.htm </HtmlFileName> |
| | | <LongName> 1097 - Disclosure - Reconciliation of Statutory Federal Income Tax Rate to Effective Income Tax Rate (Detail) </LongName> |
| | | <ReportType> Sheet </ReportType> |
| | | <Role> http://imetrix.edgar-online.com/taxonomy/role/DisclosureReconciliationOfStatutoryFederalIncomeTaxRateToEffectiveIncomeTaxRate </Role> |
| | | <ShortName> Reconciliation of Statutory Federal Income Tax Rate to Effective Income Tax Rate (Detail) </ShortName> |
| | | <MenuCategory> Details </MenuCategory> |
| | | <Position> 96 </Position> |
| | | </Report> |
| | <Report instance="ck0000839759-20181231.xml"> |
| | | <IsDefault> false </IsDefault> |
| | | <HasEmbeddedReports> false </HasEmbeddedReports> |
| | | <HtmlFileName> R97.htm </HtmlFileName> |
| | | <LongName> 1098 - Disclosure - Statutory Financial Information and Dividend Limitations - Additional Information (Detail) </LongName> |
| | | <ReportType> Sheet </ReportType> |
| | | <Role> http://imetrix.edgar-online.com/taxonomy/role/DisclosureStatutoryFinancialInformationAndDividendLimitationsAdditionalInformation </Role> |
| | | <ShortName> Statutory Financial Information and Dividend Limitations - Additional Information (Detail) </ShortName> |
| | | <MenuCategory> Details </MenuCategory> |
| | | <Position> 97 </Position> |
| | | </Report> |
| | <Report instance="ck0000839759-20181231.xml"> |
| | | <IsDefault> false </IsDefault> |
| | | <HasEmbeddedReports> false </HasEmbeddedReports> |
| | | <HtmlFileName> R98.htm </HtmlFileName> |
| | | <LongName> 1099 - Disclosure - Benefit Plans - Additional Information (Detail) </LongName> |
| | | <ReportType> Sheet </ReportType> |
| | | <Role> http://imetrix.edgar-online.com/taxonomy/role/DisclosureBenefitPlansAdditionalInformation </Role> |
| | | <ShortName> Benefit Plans - Additional Information (Detail) </ShortName> |
| | | <MenuCategory> Details </MenuCategory> |
| | | <Position> 98 </Position> |
| | | </Report> |
| | <Report instance="ck0000839759-20181231.xml"> |
| | | <IsDefault> false </IsDefault> |
| | | <HasEmbeddedReports> false </HasEmbeddedReports> |
| | | <HtmlFileName> R99.htm </HtmlFileName> |
| | | <LongName> 1100 - Disclosure - Schedule of Components of Other Comprehensive Income on Pre-Tax and After-Tax Basis (Detail) </LongName> |
| | | <ReportType> Sheet </ReportType> |
| | | <Role> http://imetrix.edgar-online.com/taxonomy/role/DisclosureScheduleOfComponentsOfOtherComprehensiveIncomeOnPreTaxAndAfterTaxBasis </Role> |
| | | <ShortName> Schedule of Components of Other Comprehensive Income on Pre-Tax and After-Tax Basis (Detail) </ShortName> |
| | | <MenuCategory> Details </MenuCategory> |
| | | <Position> 99 </Position> |
| | | </Report> |
| | <Report instance="ck0000839759-20181231.xml"> |
| | | <IsDefault> false </IsDefault> |
| | | <HasEmbeddedReports> false </HasEmbeddedReports> |
| | | <HtmlFileName> R100.htm </HtmlFileName> |
| | | <LongName> 1101 - Disclosure - Schedule I - Summary of Investments Other Than Investments in Related Parties (Detail) </LongName> |
| | | <ReportType> Sheet </ReportType> |
| | | <Role> http://imetrix.edgar-online.com/taxonomy/role/DisclosureScheduleISummaryOfInvestmentsOtherThanInvestmentsInRelatedParties </Role> |
| | | <ShortName> Schedule I - Summary of Investments Other Than Investments in Related Parties (Detail) </ShortName> |
| | | <MenuCategory> Details </MenuCategory> |
| | | <Position> 100 </Position> |
| | | </Report> |
| | <Report instance="ck0000839759-20181231.xml"> |
| | | <IsDefault> false </IsDefault> |
| | | <HasEmbeddedReports> false </HasEmbeddedReports> |
| | | <HtmlFileName> R101.htm </HtmlFileName> |
| | | <LongName> 1102 - Disclosure - Schedule IV - Reinsurance (Detail) </LongName> |
| | | <ReportType> Sheet </ReportType> |
| | | <Role> http://imetrix.edgar-online.com/taxonomy/role/DisclosureScheduleIVReinsurance </Role> |
| | | <ShortName> Schedule IV - Reinsurance (Detail) </ShortName> |
| | | <MenuCategory> Details </MenuCategory> |
| | | <Position> 101 </Position> |
| | | </Report> |
| | <Report instance="ck0000839759-20181231.xml"> |
| | | <IsDefault> false </IsDefault> |
| | | <HasEmbeddedReports> false </HasEmbeddedReports> |
| | | <HtmlFileName> R102.htm </HtmlFileName> |
| | | <LongName> 1103 - Disclosure - Schedule V - Valuation Allowances and Qualifying Accounts (Detail) </LongName> |
| | | <ReportType> Sheet </ReportType> |
| | | <Role> http://imetrix.edgar-online.com/taxonomy/role/DisclosureScheduleVValuationAllowancesAndQualifyingAccounts </Role> |
| | | <ShortName> Schedule V - Valuation Allowances and Qualifying Accounts (Detail) </ShortName> |
| | | <MenuCategory> Details </MenuCategory> |
| | | <Position> 102 </Position> |
| | | </Report> |
| | <Report> |
| | | <IsDefault> false </IsDefault> |
| | | <HasEmbeddedReports> false </HasEmbeddedReports> |
| | | <LongName> All Reports </LongName> |
| | | <ReportType> Book </ReportType> |
| | | <ShortName> All Reports </ShortName> |
| | | </Report> |
| | </MyReports> |
| <InputFiles> |
| | <File> ck0000839759-20181231.xml </File> |
| | <File> ck0000839759-20181231.xsd </File> |
| | <File> ck0000839759-20181231_cal.xml </File> |
| | <File> ck0000839759-20181231_def.xml </File> |
| | <File> ck0000839759-20181231_lab.xml </File> |
| | <File> ck0000839759-20181231_pre.xml </File> |
| | </InputFiles> |
| <SupplementalFiles/> |
| <BaseTaxonomies> |
| | <BaseTaxonomy> http://fasb.org/srt/2018-01-31 </BaseTaxonomy> |
| | <BaseTaxonomy> http://xbrl.sec.gov/stpr/2018-01-31 </BaseTaxonomy> |
| | <BaseTaxonomy> http://xbrl.sec.gov/dei/2018-01-31 </BaseTaxonomy> |
| | <BaseTaxonomy> http://xbrl.sec.gov/invest/2013-01-31 </BaseTaxonomy> |
| | <BaseTaxonomy> http://fasb.org/us-gaap/2018-01-31 </BaseTaxonomy> |
| | </BaseTaxonomies> |
| <HasPresentationLinkbase> true </HasPresentationLinkbase> |
| <HasCalculationLinkbase> true </HasCalculationLinkbase> |
| </FilingSummary> |