Restatement (Details) (USD $)	3 Months Ended	12 Months Ended
	Dec. 31, 2010	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Sep. 30, 2011	Jun. 30, 2011	Mar. 31, 2011	Dec. 31, 2009
Goodwill impairment		$ 0	$ 0	$ 5,597,000
Net income (loss)	(1,289,000)	16,187,000	(68,295,000)	11,367,000
Comprehensive income (loss)	(3,657,000)	15,804,000	(67,163,000)	11,401,000
Noninterest expenses	22,408,000	63,322,000	90,201,000	69,230,000
Total assets	2,814,944,000	2,122,255,000	2,377,276,000	2,814,944,000	2,151,153,000	2,264,123,000	2,268,264,000	2,566,895,000	2,654,898,000	2,773,431,000
Shareholders' equity	372,215,000	246,056,000	301,589,000	372,215,000	244,821,000	309,003,000	306,046,000	361,427,000	371,333,000	373,753,000	309,778,000
Basic earnings per common share	$ (0.12)	$ 0.64	$ (3.73)	$ 0.40
Diluted earnings per common share	$ (0.12)	$ 0.64	$ (3.73)	$ 0.40
Previously Reported [Member]
Net income (loss)	4,308,000			16,964,000
Comprehensive income (loss)	1,940,000			16,998,000
Noninterest expenses	16,811,000			63,633,000
Total assets	2,820,541,000		2,382,873,000	2,820,541,000	2,156,750,000	2,269,720,000	2,273,861,000	2,572,492,000	2,660,495,000	2,779,028,000
Shareholders' equity	377,812,000		307,186,000	377,812,000	250,418,000	314,600,000	311,643,000	367,024,000	376,930,000	379,350,000
Basic earnings per common share	$ 0.17			$ 0.71
Diluted earnings per common share	$ 0.17			$ 0.71
Adjustments [Member]
Net income (loss)	(5,597,000)			(5,597,000)
Comprehensive income (loss)	(5,597,000)			(5,597,000)
Noninterest expenses	5,597,000			5,597,000
Total assets	(5,597,000)		(5,597,000)	(5,597,000)	(5,597,000)	(5,597,000)	(5,597,000)	(5,597,000)	(5,597,000)	(5,597,000)
Shareholders' equity	$ (5,597,000)		$ (5,597,000)	$ (5,597,000)	$ (5,597,000)	$ (5,597,000)	$ (5,597,000)	$ (5,597,000)	$ (5,597,000)	$ (5,597,000)
Basic earnings per common share	$ (0.29)			$ (0.31)
Diluted earnings per common share	$ (0.29)			$ (0.31)