Note 3 - Inventories (Details Textual) - USD ($)	3 Months Ended		6 Months Ended
	Sep. 30, 2017	Oct. 01, 2016	Sep. 30, 2017	Oct. 01, 2016
Inventory, LIFO Reserve	$ 151,096,000	$ 143,650,000	$ 151,096,000	$ 143,650,000
Inventory, LIFO Reserve, Period Charge	$ 10,398,000	$ 2,476,000	$ 17,841,000	$ 4,375,000