Note 5 - Retirement Plans (Details) - Components of Net Periodic Benefit Cost for Pension Plans - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Components of Net Periodic Benefit Cost for Pension Plans [Abstract]
Service cost	$ 1,405	$ 1,300	$ 3,116	$ 2,644
Interest cost	3,194	1,034	4,448	2,103
Expected return on plan assets	(3,710)	(1,057)	(5,114)	(2,151)
Loss amortization	900	244	1,740	496
Net periodic cost	$ 1,789	$ 1,521	$ 4,190	$ 3,092