Note 6 - Retirement Plans - Net Periodic Benefit Cost (Details) - USD ($) $ in Thousands	3 Months Ended
	Jun. 30, 2018	Jul. 01, 2017
Service Cost	$ 2,442	$ 1,981
Interest Cost	2,243	1,985
Expected Return on Plan Assets	(3,596)	(3,482)
Amortization of Prior Service Cost	30
Amortization of Net Gain	303	30
Net Periodic Benefit Cost	$ 1,422	$ 514