Unaudited Condensed Consolidated Statements of Cash Flows (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2014	Mar. 31, 2013
Operating Activities
Net income	$ 26,730	$ 20,768
Adjustments to reconcile net income to net cash provided by operating activities:
Provision for loan losses	1,122	2,100
Net amortization of investment securities premiums and discounts	7,619	21,411
Loans held for sale originated or acquired	(116,771)	(263,004)
Proceeds from sales of loans held for sale	135,309	348,970
Gain on sale of loans	(3,595)	(9,089)
Loss on sale of investments	51	137
Stock-based compensation expense, net of tax benefits	453	347
Excess tax deficiencies from stock-based compensation	14	97
Depreciation of premises and equipment	2,685	2,338
Gain on sale of other real estate owned and writedowns, net	(524)	(202)
Amortization of core deposit intangibles	710	486
Net decrease (increase) in accrued interest receivable	624	(1,254)
Net (increase) decrease in other assets	(4,927)	8,100
Net decrease in accrued interest payable	(332)	(580)
Net increase (decrease) in other liabilities	4,751	(1,565)
Net cash provided by operating activities	53,919	129,060
Investing Activities
Sales of available-for-sale securities	788	3,839
Maturities, prepayments and calls of available-for-sale securities	138,272	573,462
Purchases of available-for-sale securities	(58,192)	(573,174)
Maturities, prepayments and calls of held-to-maturity securities	3,930	0
Purchases of held-to-maturity securities	(5,618)	0
Principal collected on loans	323,418	255,672
Loans originated or acquired	(358,240)	(289,693)
Net addition of premises and equipment and other real estate owned	(1,771)	(2,654)
Proceeds from sale of other real estate owned	4,000	7,493
Net cash provided by (used in) investment activities	46,587	(25,055)
Financing Activities
Net increase in deposits	44,498	8,754
Net increase in securities sold under agreements to repurchase	13,928	22,997
Net decrease in Federal Home Loan Bank advances	(153,438)	(195,009)
Net (decrease) increase in other borrowed funds	(283)	280
Excess tax deficiencies from stock-based compensation	(14)	(97)
Proceeds from stock options exercised	837	1,087
Net cash used in financing activities	(94,472)	(161,988)
Net increase (decrease) in cash and cash equivalents	6,034	(57,983)
Cash and cash equivalents at beginning of period	155,657	187,040
Cash and cash equivalents at end of period	161,691	129,057
Supplemental Disclosure of Cash Flow Information
Cash paid during the period for interest	6,972	8,038
Cash paid during the period for income taxes	818	100
Supplemental Disclosure of Non-Cash Investing Activities
Transfer of investment securities from available-for-sale to held-to-maturity	484,583	0
Sale and refinancing of other real estate owned	157	611
Transfer of loans to other real estate owned	$ 4,105	$ 6,683