Consolidated Statements of Cash Flows (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Operating Activities
Net income	$ 106,841	$ 100,636	$ 93,047
Adjustments to reconcile net income to net cash provided by operating activities:
Provision for loan losses	30,328	49,546	77,112
Depreciation and amortization	25,273	25,646	26,489
Net amortization (accretion) of securities	9,187	3,264	(110)
Securities gains, net	(80)	(2,329)	(5,467)
Gains on sales of loans, net	(11,952)	(15,317)	(21,705)
Decrease in FDIC indemnification asset	185	0	0
Bargain purchase gain on acquisition	(7,456)	0	0
Deferred income tax benefit	(9,683)	(6,389)	(4,477)
Proceeds from sales of loans held for sale	981,349	1,164,541	1,627,971
Purchases and originations of loans held for sale	(1,003,803)	(1,127,346)	(1,553,674)
Originations and sales of mortgage servicing rights	(14,160)	(16,885)	(9,590)
Net decrease (increase) in other assets	34,238	1,588	(61,545)
Net increase (decrease) in other liabilities	2,609	736	(1,391)
Other operating activities, net	30,713	29,087	5,657
Net cash provided by operating activities	173,589	206,778	172,317
Investing Activities
Proceeds from calls and maturities of securities held to maturity	83,219	92,324	37,217
Proceeds from calls and maturities of securities available for sale	749,149	650,419	388,781
Proceeds from sales of securities available for sale	22,996	65,074	188,460
Purchases of securities held to maturity	0	0	(10,428)
Purchases of securities available for sale	(1,026,936)	(1,227,199)	(691,195)
Net decrease (increase) in federal funds sold and securities purchased under reverse repurchase agreements	3,515	(5,399)	17,027
Net decrease in loans	141,988	138,071	256,885
Purchases of premises and equipment	(12,184)	(6,720)	(6,279)
Proceeds from sales of premises and equipment	537	183	623
Proceeds from sales of other real estate	54,104	48,019	18,290
Net cash received in business combination	78,896	0	0
Net cash provided by (used in) investing activities	95,284	(245,228)	199,381
Financing Activities
Net increase (decrease) in deposits	317,447	(143,898)	364,595
Net (decrease) increase in federal funds purchased and securities sold under repurchase agreements	(95,638)	47,106	(158,097)
Net (decrease) increase in short-term borrowings	(389,666)	147,689	(518,504)
Proceeds from long-term FHLB advances	0	0	75,000
Payments from calls of long-term FHLB advances	(309)	0	0
Redemption of junior subordinated debt securities	0	(8,248)	0
Common stock dividends	(59,485)	(59,302)	(53,295)
Common stock issued-net, long-term incentive plan	(595)	1,273	593
Excess tax benefit from stock-based compensation arrangements	454	1,855	591
Repurchase of preferred stock	0	0	(215,000)
Preferred stock dividends	0	0	(11,288)
Proceeds from issuance of common stock, net	0	0	109,296
Repurchase of common stock warrant	0	0	(10,000)
Net cash used in financing activities	(227,792)	(13,525)	(416,109)
Increase (decrease) in cash and cash equivalents	41,081	(51,975)	(44,411)
Cash and cash equivalents at beginning of year	161,544	213,519	257,930
Cash and cash equivalents at end of year	$ 202,625	$ 161,544	$ 213,519