Note 4 - Inventories (Details Textual) - USD ($) $ in Thousands	12 Months Ended
Mar. 31, 2022	Mar. 31, 2021
Inventory, LIFO Reserve	$ 164,493	$ 128,672
Inventory, LIFO Reserve, Period Charge	$ 35,800	$ 15,600

The change in the inventory reserve representing the cumulative difference in cost between the first in, first out and the last in, first out inventory valuation methods, which change has been reflected in the statement of income during the period.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 330
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SAB Topic 5.L)
-URI https://asc.fasb.org/extlink&oid=27011343&loc=d3e99989-122729

Name:	us-gaap_InventoryLIFOReservePeriodCharge
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration