Note 10 - Income Taxes (Details) - Effective Income Tax Rate Reconciliation (USD $) In Thousands, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Effective Income Tax Rate Reconciliation [Abstract]
Taxes at federal statutory rate									$ 25,484	$ 21,248	$ 19,662
Taxes at federal statutory rate									35.00%	35.00%	35.00%
Increase (reduction) in taxes resulting from:
State and local income tax, net of Federal income tax benefit									4,980	3,648	3,320
State and local income tax, net of Federal income tax benefit									6.80%	6.00%	5.90%
Other									(1,891)	(1,940)	(1,135)
Other									(2.60%)	(3.20%)	(2.00%)
Taxes at effective rate	$ 6,988	$ 7,060	$ 7,598	$ 6,927	$ 6,458	$ 6,024	$ 6,155	$ 4,319	$ 28,573	$ 22,956	$ 21,847
Taxes at effective rate									39.20%	37.80%	38.90%