Condensed Financial Information - Parent Company Only Cash Flows (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Cash Flow From Operating Activities [Line Items]
Net Income	$ 145,573	$ 128,332	$ 73,924
Adjustments to Reconcile Net Income to Net Cash Provided by Operating Activities [Abstract]
Stock-based compensation	4,249	1,996	1,781
Decrease (increase) in other assets	32,084	(9,173)	(83,777)
Increase (decrease) in other liabilities and payable to non-bank subsidiaries	(17,126)	(24,939)	(9,334)
Total adjustments	226,425	156,477	108,658
Net cash provided by operating activities	371,998	284,809	182,582
Cash Flow From Investing Activities [Abstract]
Net cash (used in) provided by investing activities	(231,776)	145,949	(582,888)
Cash Flows From Financing Activities [Abstract]
Net decrease in short-term borrowings	(77,044)	(194,863)	(893,830)
Repayments of long-term debt	(104,610)	(469,223)	(247,024)
Redemption of preferred stock and common stock warrant	0	(387,300)	0
Net proceeds from issuance of common stock	6,835	231,510	7,419
Dividends paid	(33,917)	(35,003)	(58,913)
Net cash (used in) provided by financing activities	(46,578)	(516,312)	353,650
Net Increase (Decrease) in Cash and Cash Equivalents	93,644	(85,554)	(46,656)
Parent [Member]
Cash Flow From Operating Activities [Line Items]
Net Income	145,573	128,332	73,924
Adjustments to Reconcile Net Income to Net Cash Provided by Operating Activities [Abstract]
Stock-based compensation	4,249	1,996	1,781
Decrease (increase) in other assets	2,086	(11,389)	6,489
Equity in undistributed net (income) loss of subsidiaries	(76,461)	(84,876)	65,579
Increase (decrease) in other liabilities and payable to non-bank subsidiaries	18,428	242,921	(35,312)
Total adjustments	(51,698)	148,652	38,537
Net cash provided by operating activities	93,875	276,984	112,461
Cash Flow From Investing Activities [Abstract]
Investments in bank subsidiaries	(15,000)	(86,300)	(53,000)
Investments in non-bank subsidiaries	(41,125)	0	(10,000)
Line of credit to non-bank subsidiary	0	0	88,114
Net cash (used in) provided by investing activities	(56,125)	(86,300)	25,114
Cash Flows From Financing Activities [Abstract]
Net decrease in short-term borrowings	0	0	(86,000)
Repayments of long-term debt	(10,619)	0	0
Redemption of preferred stock and common stock warrant	0	(387,300)	0
Net proceeds from issuance of common stock	6,835	231,510	7,419
Dividends paid	(33,917)	(35,003)	(58,913)
Net cash (used in) provided by financing activities	(37,701)	(190,793)	(137,494)
Net Increase (Decrease) in Cash and Cash Equivalents	49	(109)	81
Cash and Cash Equivalents at Beginning of Year	10	119	38
Cash and Cash Equivalents at End of Year	$ 59	$ 10	$ 119