Parent Company Financial Information (Condensed Statements of Cash Flows) (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Operating Activities
Net Income (Loss)	$ 46,143	$ 48,037	$ 30,784
Adjustments to reconcile net income to net cash provided by operating activities:
Stock-based compensation expense	1,622	1,635	1,424
Net cash provided by operating activities	134,899	86,424	124,136
Investing Activities
Proceeds from termination of trust subsidiaries	0	774	0
Net cash provided by investing activities	8,403	(23,270)	278,465
Financing Activities
Cash dividends paid	(38,824)	(10,660)	(1,461)
Repayment of long-term subordinated debt	0	(25,774)	0
Proceeds from issuance of common stock	0	0	229,129
Purchase and retirement of common stock	0	(32)	0
Proceeds from exercise of stock options	713	848	923
Excess tax benefit from stock-based compensation	0	98	25
Net cash provided by financing activities	76,335	(282,995)	(193,545)
Increase (decrease) in cash and cash equivalents	219,637	(219,841)	209,056
Cash and cash equivalents at beginning of period	294,289	514,130	305,074
Cash and cash equivalents at end of period	513,926	294,289	514,130
Parent [Member]
Operating Activities
Net Income (Loss)	46,143	48,037	30,784
Adjustments to reconcile net income to net cash provided by operating activities:
Equity in undistributed earnings of subsidiaries	2,020	(49,180)	(30,847)
Stock-based compensation expense	1,622	1,635	1,424
Net changes in other assets and liabilities	(264)	315	(769)
Net cash provided by operating activities	49,521	807	592
Investing Activities
Proceeds from termination of trust subsidiaries	0	774	0
Net cash provided by investing activities	0	774	0
Financing Activities
Cash dividends paid	(38,824)	(10,660)	(4,302)
Repayment of long-term subordinated debt	0	(25,774)	0
Proceeds from issuance of common stock	0	0	229,129
Purchase and retirement of common stock	0	(32)	0
Proceeds from exercise of stock options	713	848	948
Downstream stock offering proceeds to the Bank	0	(50,000)	(70,000)
Excess tax benefit from stock-based compensation	0	98	0
Purchase and retirement of preferred stock	0	0	(80,200)
Net cash provided by financing activities	(38,111)	(85,520)	75,575
Increase (decrease) in cash and cash equivalents	11,410	(83,939)	76,167
Cash and cash equivalents at beginning of period	75,234	159,173	83,006
Cash and cash equivalents at end of period	$ 86,644	$ 75,234	$ 159,173