Note 13 - Stockholders' Equity and Earnings per Share (Detail) - Earnings per Share (USD $) In Thousands, except Share data, 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
Net income	$ 28,459	$ 30,509	$ 30,011	$ 29,064	$ 27,854	$ 26,235	$ 24,452	$ 22,214	$ 117,438	$ 100,150	$ 11,565
Dividends on preferred stock	4,127	4,123	4,121	4,117	4,114	4,111	4,107	4,105	(16,488)	(16,437)	(16,388)
Basic EPS, income/(loss)	24,179	26,235	25,740	24,796	23,587	21,973	20,195	17,958	100,950	83,713	(4,823)
Basic EPS, income/(loss) (in Shares)									78,719,133	78,633,317	77,073,954
Basic EPS, income/(loss) (in Dollars per share)	$ 0.31	$ 0.33	$ 0.33	$ 0.32	$ 0.30	$ 0.28	$ 0.26	$ 0.23	$ 1.28	$ 1.06	$ (0.06)
Effect of dilutive stock options (in Shares)									4,164	7,335
Diluted EPS, income/(loss)									$ 100,950	$ 83,713	$ (4,823)
Diluted EPS, income/(loss) (in Shares)									78,723,297	78,640,652	77,073,954
Diluted EPS, income/(loss) (in Dollars per share)	$ 0.31	$ 0.33	$ 0.33	$ 0.32	$ 0.30	$ 0.28	$ 0.26	$ 0.23	$ 1.28	$ 1.06	$ (0.06)