Note 5 - Inventories (Details Textual) - USD ($)	3 Months Ended	9 Months Ended
Dec. 26, 2020	Dec. 28, 2019	Dec. 26, 2020	Dec. 28, 2019	Mar. 31, 2020
Inventory, LIFO Reserve	$ 139,999,000	$ 153,884,000	$ 139,999,000	$ 153,884,000	$ 144,267,000
Inventory, LIFO Reserve, Period Charge	$ 4,656,000	$ 11,337,000	$ 4,268,000	$ 7,457,000

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
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-Name Accounting Standards Codification
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Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
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-Name Accounting Standards Codification
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Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration