Note 10 - Income Taxes - Income Tax Provisions (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Federal:
Federal tax provision, current									$ 34,996	$ 25,319	$ 18,052
Federal tax provision, deferred									(1,416)	(3,476)	2,860
Total federal tax provision									33,580	21,843	20,912
State and Local:
State and local tax provision, current									7,647	7,059	6,369
State and local tax provision, deferred									(124)	(1,735)	1,292
Total state and local tax provision									7,523	5,324	7,661
Total income tax provision	$ 8,116	$ 6,655	$ 20,717	$ 5,615	$ 5,439	$ 6,661	$ 9,521	$ 5,546	$ 41,103	$ 27,167	$ 28,573