Note 6 - Retirement Plans (Details Textual) - USD ($)	3 Months Ended
	Jun. 30, 2018	Jul. 01, 2017
Defined Benefit Plan, Plan Assets, Contributions by Employer	$ 0	$ 0
Other Nonoperating Income (Expense) [Member]
Defined Benefit Plan, Non-Service Cost	$ 1,020,000	$ 1,467,000