Segment Information (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012	Dec. 31, 2012
Segment Reporting Information [Line Items]
Interest income	$ 2,273	$ 2,789
Interest expense	13,863	23,612
Provision for credit losses	0	4,000
Noninterest Income	37,566	31,587
Noninterest expense	81,929	88,649
Income before income taxes	32,531	13,291
Assets	9,256,436	9,502,281	9,236,910
Community Banking [Member]
Segment Reporting Information [Line Items]
Interest income	83,690	92,787
Interest expense	12,419	22,493
Net interest income	71,271	70,294
Provision for credit losses	0	4,000
Noninterest Income	21,185	19,178
Noninterest expense	62,453	72,776
Income before income taxes	30,003	12,696
Assets	8,942,231	9,529,511
Home Loan Division [Member]
Segment Reporting Information [Line Items]
Interest income	7,067	5,178
Interest expense	0	0
Net interest income	7,067	5,178
Provision for credit losses	0	0
Noninterest Income	16,373	12,761
Noninterest expense	17,472	14,614
Income before income taxes	5,968	3,325
Assets	308,209	1,057
Intersegment Elimination [Member]
Segment Reporting Information [Line Items]
Interest income	0	0
Interest expense	1,444	1,119
Net interest income	(1,444)	(1,119)
Provision for credit losses	0	0
Noninterest Income	8	(352)
Noninterest expense	2,004	1,259
Income before income taxes	(3,440)	(2,730)
Assets	5,996	(28,287)
Reportable Segment [Member]
Segment Reporting Information [Line Items]
Interest income	90,757	97,965
Interest expense	13,863	23,612
Net interest income	76,894	74,353
Provision for credit losses	0	4,000
Noninterest Income	37,566	31,587
Noninterest expense	81,929	88,649
Income before income taxes	$ 32,531	$ 13,291