Note 5 - Stock-based Compensation (Details) - Tax Short-fall from Share-based Payment Arrangements - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Tax Short-fall from Share-based Payment Arrangements [Abstract]
Tax benefit/(short-fall) of tax deductions in excess of grant-date fair value	$ (3,298)	$ (4,395)
Benefit of tax deductions on grant-date fair value	3,302	4,442
Total benefit of tax deductions	$ 4	$ 47