Note 7 - Employee Benefit Plans (Details) - Net Periodic Pension Cost - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Net Periodic Pension Cost [Abstract]
Service cost	$ 1,054	$ 1,020	$ 3,162	$ 3,060
Interest cost	1,206	1,186	3,618	3,558
Expected return on plan assets	(1,345)	(1,249)	(4,036)	(3,747)
Amortization of prior service cost	(84)	(84)	(253)	(252)
Amortization of net (gain) loss	1,065	756	3,195	2,268
Net periodic pension cost	$ 1,896	$ 1,629	$ 5,686	$ 4,887