Quarterly Financial Information (Details) (USD $)	3 Months Ended								12 Months Ended
	Dec. 31, 2011	Sep. 30, 2011	Jun. 30, 2011	Mar. 31, 2011	Dec. 31, 2010	Sep. 30, 2010	Jun. 30, 2010	Mar. 31, 2010	Dec. 31, 2011		Dec. 31, 2010		Dec. 31, 2009
Quarterly Financial Information [Abstract]
Interest income	$ 121,917,000	$ 126,527,000	$ 128,417,000	$ 124,892,000	$ 130,677,000	$ 132,946,000	$ 115,604,000	$ 109,369,000	$ 501,753,000		$ 488,596,000		$ 423,732,000
Interest expense	15,262,000	18,993,000	19,056,000	19,990,000	23,562,000	24,629,000	23,304,000	22,317,000	73,301,000		93,812,000		103,024,000
Net interest income	106,655,000	107,534,000	109,361,000	104,902,000	107,115,000	108,317,000	92,300,000	87,052,000	428,452,000		394,784,000		320,708,000
Provision for non-covered loan and lease losses	6,642,000	9,089,000	15,459,000	15,030,000	17,567,000	24,228,000	29,767,000	42,106,000	46,220,000		113,668,000		209,124,000
Provision for covered loan and lease losses	698,000	4,420,000	3,755,000	7,268,000	4,484,000	667,000			16,141,000		5,151,000
Non-interest income	18,128,000	24,778,000	19,627,000	21,585,000	15,161,000	12,133,000	18,563,000	30,047,000	84,118,000		75,904,000		73,516,000
Non-interest expense	85,339,000	86,224,000	83,207,000	84,201,000	87,864,000	85,170,000	74,833,000	69,871,000	338,971,000		317,738,000		379,403,000
Income (loss) before provision for (benefit from) income taxes	32,104,000	32,579,000	26,567,000	19,988,000	12,361,000	10,385,000	6,263,000	5,122,000	111,238,000		34,131,000		(194,303,000)
Provision for (benefit from) income taxes	10,722,000	10,717,000	8,782,000	6,521,000	4,203,000	2,194,000	2,800,000	(3,392,000)	36,742,000		5,805,000		(40,937,000)
Net income	21,382,000	21,862,000	17,785,000	13,467,000	8,158,000	8,191,000	3,463,000	8,514,000	74,496,000		28,326,000		(153,366,000)
Preferred stock dividends											3,686,000		10,739,000
Dividends and undistributed earnings allocated to participating securities	103,000	105,000	86,000	62,000	18,000	18,000	16,000	15,000	356,000	[1]	67,000	[1]	30,000	[1]
Net earnings (loss) available to common shareholders	21,279,000	21,757,000	17,699,000	13,405,000	8,140,000	8,173,000	3,447,000	(3,693,000)	74,140,000		16,067,000		(166,262,000)
Basic earnings (loss) per common share	$ 0.19	$ 0.19	$ 0.15	$ 0.12	$ 0.07	$ 0.07	$ 0.03	$ (0.04)	$ 0.65		$ 0.15		$ (2.36)
Diluted earnings (loss) per common share	$ 0.19	$ 0.19	$ 0.15	$ 0.12	$ 0.07	$ 0.07	$ 0.03	$ (0.04)	$ 0.65		$ 0.15		$ (2.36)
Cash dividends declared per common share	$ 0.07	$ 0.07	$ 0.05	$ 0.05	$ 0.05	$ 0.05	$ 0.05	$ 0.05	$ 27,471,000		$ 22,032,000		$ 14,737,000

[1] Represents dividends paid and undistributed earnings allocated to nonvested restricted stock awards.