Segment Information (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012	Dec. 31, 2012
Segment Reporting Information [Line Items]
Interest income	$ 2,248	$ 2,517	$ 4,521	$ 5,306
Interest expense	13,603	22,080	27,466	45,692
Provision for credit losses	0	4,000	0	8,000
Noninterest Income	42,003	44,741	79,569	76,328
Noninterest expense	81,678	87,607	163,607	176,256
Income before income taxes	40,739	32,044	73,270	45,335
Assets	9,939,573	9,599,513	9,939,573	9,599,513	9,236,910
Community Banking [Member]
Segment Reporting Information [Line Items]
Interest income	86,699	94,634	170,389	187,421
Interest expense	12,142	21,241	24,561	43,734
Net interest income	74,557	73,393	145,828	143,687
Provision for credit losses	0	4,000	0	8,000
Noninterest Income	17,816	18,597	39,001	37,775
Noninterest expense	55,906	68,127	118,359	140,903
Income before income taxes	36,467	19,863	66,470	32,559
Assets	9,608,919	9,593,152	9,608,919	9,593,152
Home Loan Division [Member]
Segment Reporting Information [Line Items]
Interest income	7,318	6,356	14,385	11,534
Interest expense	0	0	0	0
Net interest income	7,318	6,356	14,385	11,534
Provision for credit losses	0	0	0	0
Noninterest Income	24,660	25,940	41,033	38,701
Noninterest expense	26,338	20,150	43,810	34,764
Income before income taxes	5,640	12,146	11,608	15,471
Assets	331,860	5,720	331,860	5,720
Intersegment Elimination [Member]
Segment Reporting Information [Line Items]
Interest income	0	0	0	0
Interest expense	1,461	839	2,905	1,958
Net interest income	(1,461)	(839)	(2,905)	(1,958)
Provision for credit losses	0	0	0	0
Noninterest Income	(473)	204	(465)	(148)
Noninterest expense	(566)	(670)	1,438	589
Income before income taxes	(1,368)	35	(4,808)	(2,695)
Assets	(1,206)	641	(1,206)	641
Reportable Segment [Member]
Segment Reporting Information [Line Items]
Interest income	94,017	100,990	184,774	198,955
Interest expense	13,603	22,080	27,466	45,692
Net interest income	80,414	78,910	157,308	153,263
Provision for credit losses	0	4,000	0	8,000
Noninterest Income	42,003	44,741	79,569	76,328
Noninterest expense	81,678	87,607	163,607	176,256
Income before income taxes	$ 40,739	$ 32,044	$ 73,270	$ 45,335