Note 12 - Income Taxes - Reconciliation of Income Tax Expense (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Tax provision at federal statutory rate	$ 28,072	$ 29,846	$ 29,818
State, net of federal benefit	1,783	1,767	2,207
Nondeductible expenses	156	351	363
Insurance expense	27	6	27
Other, net	283	(372)	439
Unrecognized tax benefits	716	2,674	512
Expiration of statute of limitations	(1,368)	(2,141)	(1,542)
	1,597	2,285	2,006
Effective income tax expense	$ 29,669	$ 32,131	$ 31,824