Note 13 - Stockholders' Equity and Earnings per Share (Details) - Earnings per Share (USD $) In Thousands, except Share data, 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
Earnings Per Share [Abstract]
Net income	$ 32,042	$ 32,629	$ 30,066	$ 28,998	$ 28,459	$ 30,509	$ 30,011	$ 29,064	$ 123,143	$ 117,438	$ 100,150
Dividends on preferred stock		2,434	2,067	5,184	4,127	4,123	4,121	4,117	(9,685)	(16,488)	(16,437)
Basic EPS, income/(loss)	31,902	30,044	27,849	23,663	24,179	26,235	25,740	24,796	113,458	100,950	83,713
Basic EPS, income/(loss) (in Shares)									78,954,898	78,719,133	78,633,317
Basic EPS, income/(loss) (in Dollars per share)	$ 0.40	$ 0.38	$ 0.35	$ 0.30	$ 0.31	$ 0.33	$ 0.33	$ 0.32	$ 1.44	$ 1.28	$ 1.06
Effect of dilutive stock options (in Shares)									183,085	4,164	7,335
Diluted EPS, income/(loss)									$ 113,458	$ 100,950	$ 83,713
Diluted EPS, income/(loss) (in Shares)									79,137,983	78,723,297	78,640,652
Diluted EPS, income/(loss) (in Dollars per share)	$ 0.40	$ 0.38	$ 0.35	$ 0.30	$ 0.31	$ 0.33	$ 0.33	$ 0.32	$ 1.43	$ 1.28	$ 1.06