Note 7 - Income Taxes - Reconciliation of Income Tax Expense (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Statutory federal rate applied to income before income tax expense	$ 36,992	$ 23,012	$ 27,929
Current year permanent items	1,830	1,192	849
State and local taxes, net of federal tax benefit	5,056	2,831	4,050
Change in valuation allowance	(151)	(369)	(696)
Reserve for uncertain tax positions	(698)	(581)	(198)
Other items, net	389	363	(198)
Income tax expense as recorded	$ 43,418	$ 26,448	$ 31,736
Effective income tax rate	41.10%	40.20%	39.80%