Note 5 - Retirement Plans - Components of Net Periodic Benefit Cost for Pension Plans (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Service cost				$ 3,116
Interest cost	1,185		3,554	4,448
Expected return on plan assets	(1,298)		(3,892)	(5,114)
Loss amortization	153		458	1,740
Net periodic benefit cost	$ 40		$ 120	$ 4,190