Unaudited Condensed Consolidated Statements of Cash Flows (USD $) In Thousands, unless otherwise specified	9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012
Operating Activities
Net income	$ 69,098	$ 54,758
Adjustments to reconcile net income to net cash provided by operating activities:
Provision for loan losses	5,085	19,250
Net amortization of investment securities premiums and discounts	55,043	48,712
Federal Home Loan Bank stock dividends	0	(5)
Mortgage loans held for sale originated or acquired	(760,860)	(844,155)
Proceeds from sales of mortgage loans held for sale	904,066	872,659
Gain on sale of loans	(23,582)	(23,063)
Loss on sale of investments	299	0
Stock-based compensation expense, net of tax benefits	800	255
Excess tax deficiencies from stock-based compensation	219	8
Depreciation of premises and equipment	7,408	7,384
Loss on sale of other real estate owned and writedown, net	1,276	11,671
Amortization of core deposit intangibles	1,684	1,619
Net increase in accrued interest receivable	(2,628)	(4,398)
Net decrease (increase) in other assets	3,459	(3,649)
Net decrease in accrued interest payable	(1,290)	(1,172)
Net increase in other liabilities	12,526	13,082
Net cash provided by operating activities	272,603	152,956
Investing Activities
Proceeds from sales, maturities and prepayments of investment securities, available-for-sale	1,676,928	1,397,533
Purchases of investment securities, available-for-sale	(1,321,504)	(1,873,893)
Principal collected on loans	854,553	706,240
Loans originated or acquired	(1,121,384)	(716,729)
Net addition of premises and equipment and other real estate owned	(6,861)	(7,896)
Proceeds from sale of other real estate owned	18,131	28,483
Net sale (purchase) of non-marketable equity securities	583	(664)
Net cash received from acquisitions	26,155	0
Net cash provided by (used in) investment activities	126,601	(466,926)
Financing Activities
Net (decrease) increase in deposits	(301,759)	381,884
Net increase in securities sold under agreements to repurchase	24,805	156,193
Net decrease in Federal Home Loan Bank advances	(35,098)	(152,025)
Net (decrease) increase in federal funds purchased and other borrowed funds	(1,458)	264
Cash dividends paid	(21,153)	(28,052)
Excess tax deficiencies from stock-based compensation	(219)	(8)
Proceeds from stock options exercised	3,322	81
Net cash (used in) provided by financing activities	(331,560)	358,337
Net increase in cash and cash equivalents	67,644	44,367
Cash and cash equivalents at beginning of period	187,040	128,032
Cash and cash equivalents at end of period	254,684	172,399
Supplemental Disclosure of Cash Flow Information
Cash paid during the period for interest	23,120	28,721
Cash paid during the period for income taxes	17,283	18,081
Supplemental Disclosure of Non-Cash Investing Activities
Sale and refinancing of other real estate owned	3,549	1,578
Transfer of loans to other real estate owned	13,091	21,029
Fair value of common stock shares issued	45,033	0
Cash consideration for outstanding shares	24,858	0
Fair value of assets acquired	630,569	0
Liabilities assumed	$ 560,678	$ 0