Consolidated Statements of Cash Flows (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Operating Activities
Net income	$ 95,644	$ 75,516	$ 17,471
Adjustments to reconcile net income to net cash provided by operating activities:
Provision for loan losses	6,887	21,525	64,500
Net amortization of investment securities premiums and discounts	64,066	71,992	38,035
Federal Home Loan Bank stock dividends	0	(5)	(17)
Loans held for sale originated or acquired	(918,451)	(1,188,632)	(824,089)
Proceeds from sales of loans held for sale	1,084,799	1,204,431	842,337
Gain on sale of loans	(28,517)	(32,227)	(21,132)
Loss (gain) on sale of investments	299	0	(346)
Stock-based compensation expense, net of tax benefits	1,011	254	45
Excess tax deficiencies from stock-based compensation	223	8	0
Depreciation of premises and equipment	10,485	10,615	10,443
Loss on sale of other real estate owned and writedowns, net	1,450	13,311	19,727
Core deposit intangible amortization	2,401	2,110	2,473
Goodwill impairment charge	0	0	40,159
Deferred tax expense (benefit)	4,633	837	(13,308)
Net increase in accrued interest receivable	(265)	(2,809)	(4,715)
Net decrease (increase) in other assets	19,881	(3,286)	12,464
Net decrease in accrued interest payable	(1,354)	(1,150)	(1,420)
Net (decrease) increase in other liabilities	(9,097)	11,303	4,216
Net cash provided by operating activities	334,095	183,793	186,843
Investing Activities
Proceeds from sales, maturities and prepayments of investment securities, available-for-sale	1,864,334	2,041,416	1,024,508
Purchases of investment securities, available-for-sale	(1,426,262)	(2,638,054)	(1,730,244)
Principal collected on loans	1,224,222	1,034,374	958,401
Loans originated or acquired	(1,559,353)	(1,049,344)	(826,329)
Net addition of premises and equipment and other real estate owned	(8,977)	(10,730)	(17,492)
Proceeds from sale of other real estate owned	28,535	41,804	46,703
Net sale of non-marketable equity securities	583	888	15,357
Net cash received from acquisitions	26,155	0	0
Net cash provided by (used in) investment activities	149,237	(579,646)	(529,096)
Financing Activities
Net (decrease) increase in deposits	(334,672)	543,248	299,311
Net increase in securities sold under agreements to repurchase	23,886	30,865	9,240
Net (decrease) increase in Federal Home Loan Bank advances	(162,298)	(72,033)	103,905
Net (decrease) increase in federal funds purchased and other borrowed funds	(1,502)	180	(9,867)
Cash dividends paid	(44,232)	(47,472)	(37,395)
Excess tax deficiencies from stock-based compensation	(223)	(8)	0
Proceeds from stock options exercised	4,326	81	0
Net cash (used in) provided by financing activities	(514,715)	454,861	365,194
Net (decrease) increase in cash and cash equivalents	(31,383)	59,008	22,941
Cash and cash equivalents at beginning of period	187,040	128,032	105,091
Cash and cash equivalents at end of period	155,657	187,040	128,032
Supplemental Disclosure of Cash Flow Information
Cash paid during the period for interest	30,111	36,865	45,913
Cash paid during the period for income taxes	23,576	21,257	7,925
Supplemental Disclosure of Non-Cash Investing Activities
Sale and refinancing of other real estate owned	4,819	5,659	8,665
Transfer of loans to other real estate owned	15,266	27,536	79,295
Fair value of common stock shares issued	45,033	0	0
Cash consideration for outstanding shares	24,858	0	0
Fair value of assets acquired	630,569	0	0
Liabilities assumed	$ 560,678	$ 0	$ 0