Consolidated Statements of Cash Flows (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Operating Activities
Net income	$ 75,516	$ 17,471	$ 42,330
Adjustments to reconcile net income to net cash provided by operating activities:
Provision for loan losses	21,525	64,500	84,693
Net amortization of investment securities premiums and discounts	71,992	38,035	17,782
Federal Home Loan Bank stock dividends	(5)	(17)	(23)
Mortgage loans held for sale originated or acquired	(1,188,632)	(824,089)	(1,086,089)
Proceeds from sales of mortgage loans held for sale	1,204,431	842,337	1,129,592
Gain on sale of loans	(32,227)	(21,132)	(27,233)
Gain on sale of investments	0	(346)	(4,822)
Stock-based compensation expense, net of tax benefits	254	45	932
Excess tax deficiencies from stock options exercised	8	0	4
Depreciation of premises and equipment	10,615	10,443	10,808
Loss on sale of other real estate owned and writedown	13,311	19,727	15,937
Amortization of core deposit intangibles	2,110	2,473	3,180
Goodwill impairment charge	0	40,159	0
Deferred tax expense (benefit)	837	(13,308)	138
Net increase in accrued interest receivable	(2,809)	(4,715)	(517)
Net (increase) decrease in other assets	(3,286)	12,464	6,878
Net decrease in accrued interest payable	(1,150)	(1,420)	(683)
Net increase in other liabilities	11,303	4,216	1,036
Net cash provided by operating activities	183,793	186,843	193,943
Investing Activities
Proceeds from sales, maturities and prepayments of investment securities, available-for-sale	2,041,416	1,024,508	700,182
Purchases of investment securities, available-for-sale	(2,638,054)	(1,730,244)	(1,664,341)
Principal collected on loans	1,034,374	958,401	984,827
Loans originated or acquired	(1,049,344)	(826,329)	(849,222)
Net addition of premises and equipment and other real estate owned	(10,730)	(17,492)	(22,652)
Proceeds from sale of other real estate owned	41,804	46,703	30,529
Net sale (purchase) of non-marketable equity securities	888	15,357	(1,829)
Net cash used in investment activities	(579,646)	(529,096)	(822,506)
Financing Activities
Net increase in deposits	543,248	299,311	421,750
Net increase in securities sold under agreements to repurchase	30,865	9,240	36,897
Net (decrease) increase in Federal Home Loan Bank advances	(72,033)	103,905	174,774
Net decrease in Federal Reserve Bank discount window			(225,000)
Net increase (decrease) in federal funds purchased and other borrowed funds	180	(9,867)	6,404
Cash dividends paid	(47,472)	(37,395)	(37,396)
Excess tax deficiencies from stock options exercised	(8)	0	(4)
Proceeds from stock options exercised and other stock issued	81	0	145,654
Net cash provided by financing activities	454,861	365,194	523,079
Net increase (decrease) in cash and cash equivalents	59,008	22,941	(105,484)
Cash and cash equivalents at beginning of period	128,032	105,091	210,575
Cash and cash equivalents at end of period	187,040	128,032	105,091
Supplemental Disclosure of Cash Flow Information
Cash paid during the period for interest	36,865	45,913	54,318
Cash paid during the period for income taxes	21,257	7,925	9,371
Sale and refinancing of other real estate owned	5,659	8,665	10,215
Transfer of loans to other real estate owned	27,536	79,295	72,572
Retained Earnings [Member]
Operating Activities
Net income	$ 75,516	$ 17,471	$ 42,330