v3.20.1
Inventories (Narrative) (Details) - USD ($)
|
12 Months Ended |
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|
|
Inventory [Line Items] |
|
|
|
Liquidation of LIFO layer |
$ 85,000
|
$ 26,000
|
$ 64,000
|
FIFO inventory amount |
95,792,000
|
66,200,000
|
|
Finished goods |
751,000
|
1,003,000
|
|
Work in process |
87,805,000
|
59,580,000
|
|
Raw materials and supplies |
7,236,000
|
5,617,000
|
|
Housewares/ Small Appliances [Member] |
|
|
|
Inventory [Line Items] |
|
|
|
LIFO inventory amount |
32,744,000
|
27,788,000
|
|
Inventory valuation, difference below FIFO |
$ 3,982,000
|
$ 4,024,000
|
|
X |
- DefinitionThe effect of liquidating LIFO (last in first out) inventory layers on income.
+ References
+ Details
Name: |
us-gaap_EffectOfLIFOInventoryLiquidationOnIncome |
Namespace Prefix: |
us-gaap_ |
Data Type: |
xbrli:monetaryItemType |
Balance Type: |
credit |
Period Type: |
duration |
|
X |
- DefinitionThe excess of replacement or current cost over the stated LIFO (last in first out) inventory value when the LIFO inventory method is utilized.
+ References
+ Details
Name: |
us-gaap_ExcessOfReplacementOrCurrentCostsOverStatedLIFOValue |
Namespace Prefix: |
us-gaap_ |
Data Type: |
xbrli:monetaryItemType |
Balance Type: |
debit |
Period Type: |
instant |
|
X |
- DefinitionThe amount of FIFO (first in first out) inventory present at the reporting date when inventory is also valued using different valuation methods.
+ References
+ Details
Name: |
us-gaap_FIFOInventoryAmount |
Namespace Prefix: |
us-gaap_ |
Data Type: |
xbrli:monetaryItemType |
Balance Type: |
debit |
Period Type: |
instant |
|
X |
- DefinitionAmount before valuation and LIFO reserves of completed merchandise or goods expected to be sold within one year or operating cycle, if longer.
+ References
+ Details
Name: |
us-gaap_InventoryFinishedGoods |
Namespace Prefix: |
us-gaap_ |
Data Type: |
xbrli:monetaryItemType |
Balance Type: |
debit |
Period Type: |
instant |
|
X |
- DefinitionLine items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.
+ References
+ Details
Name: |
us-gaap_InventoryLineItems |
Namespace Prefix: |
us-gaap_ |
Data Type: |
xbrli:stringItemType |
Balance Type: |
na |
Period Type: |
duration |
|
X |
- DefinitionGross amount of unprocessed materials to be used in manufacturing or production process and supplies that will be consumed.
+ References
+ Details
Name: |
us-gaap_InventoryRawMaterialsAndSupplies |
Namespace Prefix: |
us-gaap_ |
Data Type: |
xbrli:monetaryItemType |
Balance Type: |
debit |
Period Type: |
instant |
|
X |
- DefinitionAmount before valuation and LIFO reserves of merchandise or goods in the production process expected to be completed within one year or operating cycle, if longer.
+ References
+ Details
Name: |
us-gaap_InventoryWorkInProcess |
Namespace Prefix: |
us-gaap_ |
Data Type: |
xbrli:monetaryItemType |
Balance Type: |
debit |
Period Type: |
instant |
|
X |
- DefinitionThe amount of LIFO (last in first out) inventory present at the reporting date when inventory is also valued using different valuation methods.
+ References
+ Details
Name: |
us-gaap_LIFOInventoryAmount |
Namespace Prefix: |
us-gaap_ |
Data Type: |
xbrli:monetaryItemType |
Balance Type: |
debit |
Period Type: |
instant |
|
X |
- Details
Name: |
us-gaap_StatementBusinessSegmentsAxis=npk_HousewaresSmallAppliancesMember |
Namespace Prefix: |
|
Data Type: |
na |
Balance Type: |
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Period Type: |
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