Note 7 - Retirement Plans - Net Periodic Benefit Cost (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Sep. 30, 2017	Oct. 01, 2016	Sep. 30, 2017	Oct. 01, 2016
Service Cost	$ 1,981	$ 2,164	$ 3,963	$ 4,328
Interest Cost	1,985	1,919	3,971	3,838
Expected Return on Plan Assets	(3,482)	(2,978)	(6,967)	(5,957)
Amortization of Actuarial Loss		679		1,358
Amortization of Transition Asset	30	27	60	55
Net Periodic Benefit Cost	$ 514	$ 1,811	$ 1,027	$ 3,622