Note 7 - Employee Benefit Plans (Details) - Net Periodic Pension Cost - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Net Periodic Pension Cost [Abstract]
Service cost	$ 1,054	$ 1,020	$ 2,108	$ 2,040
Interest cost	1,206	1,186	2,412	2,372
Expected return on plan assets	(1,345)	(1,249)	(2,691)	(2,498)
Amortization of prior service cost	(84)	(84)	(169)	(168)
Amortization of net (gain) loss	1,065	756	2,130	1,512
Net periodic pension cost	$ 1,896	$ 1,629	$ 3,790	$ 3,258