Note 12 - Income Taxes (Detail) - Income Tax Reconciliation (USD $) In Thousands, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2011	Sep. 30, 2011	Jun. 30, 2011	Mar. 31, 2011	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Tax provision at Federal statutory rate (in Dollars)									$ 64,248	$ 52,994	$ (1,072)
Tax provision at Federal statutory rate									35.00%	35.00%	35.00%
State income taxes, net of Federal income tax benefit (in Dollars)									11,772	9,477	(1,641)
State income taxes, net of Federal income tax benefit									6.40%	6.30%	53.50%
Interest on obligations of state and political subdivisions, which are exempt from Federal taxation (in Dollars)									(1,456)	(1,476)	(299)
Interest on obligations of state and political subdivisions, which are exempt from Federal taxation									(0.80%)	(1.00%)	9.80%
Low income housing and other tax credits (in Dollars)									(9,353)	(10,087)	(11,220)
Low income housing and other tax credits									(5.10%)	(6.60%)	366.20%
Other, net (in Dollars)									917	353	(397)
Other, net									0.50%	0.20%	13.00%
Total income tax expense/(benefit) (in Dollars)	$ 15,276	$ 17,686	$ 16,619	$ 16,547	$ 14,459	$ 14,162	$ 10,906	$ 11,734	$ 66,128	$ 51,261	$ (14,629)
Total income tax expense/(benefit)									36.00%	33.90%	477.50%