Note 12 - Income Taxes (Details) - Income Tax Reconciliation (USD $) In Thousands, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Income Tax Reconciliation [Abstract]
Tax provision at Federal statutory rate (in Dollars)									$ 67,752	$ 64,248	$ 52,994
Tax provision at Federal statutory rate									35.00%	35.00%	35.00%
State income taxes, net of Federal income tax benefit (in Dollars)									12,573	11,772	9,477
State income taxes, net of Federal income tax benefit									6.50%	6.40%	6.30%
Interest on obligations of state and political subdivisions, which are exempt from Federal taxation (in Dollars)									(348)	(1,456)	(1,476)
Interest on obligations of state and political subdivisions, which are exempt from Federal taxation									(0.20%)	(0.80%)	(1.00%)
Low income housing and other tax credits (in Dollars)									(10,056)	(9,353)	(10,087)
Low income housing and other tax credits									(5.20%)	(5.10%)	(6.60%)
Other, net (in Dollars)									514	917	353
Other, net									0.30%	0.50%	0.20%
Total income tax expense/(benefit) (in Dollars)	$ 17,946	$ 19,029	$ 16,573	$ 16,887	$ 15,276	$ 17,686	$ 16,619	$ 16,547	$ 70,435	$ 66,128	$ 51,261
Total income tax expense/(benefit)									36.40%	36.00%	33.90%