Noninterest Expense (Details) (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
Noninterest Expense [Abstract]
Employee compensation and benefits									$ 189,025	$ 171,643	$ 168,793
OREO operations									11,829	41,500	62,578
Occupancy and equipment									42,930	39,878	39,643
Data processing									27,091	24,171	23,116
FDIC insurance									7,493	14,328	32,088
Professional Fees									16,691	13,902	22,394
Depreciation									11,690	12,184	13,391
Advertising									12,688	10,017	11,536
Travel and entertainment									5,756	5,420	3,975
Merger and acquisition									11,976	1,012	358
Amortization of other intangible assets									6,780	4,851	4,898
Other									11,304	13,484	12,275
Total noninterest expense	$ 89,589	$ 89,408	$ 87,607	$ 88,649	$ 85,875	$ 86,620	$ 91,587	$ 88,308	$ 355,253	$ 352,390	$ 395,045