Condensed Consolidated Statements of Cash Flows (Unaudited) (USD $) In Thousands, unless otherwise specified	6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012
Operating Activities
Net income	$ 43,470	$ 35,314
Adjustments to reconcile net income to net cash provided by operating activities:
Provision for loan losses	3,178	16,550
Net amortization of investment securities premiums and discounts	39,846	29,212
Federal Home Loan Bank stock dividends	0	(5)
Mortgage loans held for sale originated or acquired	(527,853)	(500,694)
Proceeds from sales of mortgage loans held for sale	616,180	547,893
Gain on sale of loans	(16,561)	(14,335)
Gain on sale of investments	(104)	0
Stock-based compensation expense, net of tax benefits	607	236
Excess tax deficiencies from stock-based compensation	188	0
Depreciation of premises and equipment	4,742	4,943
Loss on sale of other real estate owned and writedown	987	6,814
Amortization of core deposit intangibles	991	1,087
Net increase in accrued interest receivable	(3,673)	(2,147)
Net decrease in other assets	1,584	1,001
Net decrease in accrued interest payable	(1,007)	(749)
Net increase in other liabilities	3,406	8,577
Net cash provided by operating activities	165,981	133,697
Investing Activities
Proceeds from sales, maturities and prepayments of investment securities, available-for-sale	1,165,981	871,472
Purchases of investment securities, available-for-sale	(1,224,241)	(1,154,990)
Principal collected on loans	513,255	441,318
Loans originated or acquired	(650,378)	(478,541)
Net addition of premises and equipment and other real estate owned	(3,167)	(5,501)
Proceeds from sale of other real estate owned	11,066	18,073
Net sale (purchase) of non-marketable equity securities	60	(671)
Net cash received from acquisitions	12,123	0
Net cash used in investment activities	(175,301)	(308,840)
Financing Activities
Net (decrease) increase in deposits	(261,461)	161,056
Net increase in securities sold under agreements to repurchase	10,516	208,141
Net increase (decrease) in Federal Home Loan Bank advances	214,965	(163,017)
Net (decrease) increase in federal funds purchased and other borrowed funds	(1,471)	50
Cash dividends paid	(10,099)	(18,700)
Excess tax deficiencies from stock-based compensation	(188)	0
Proceeds from stock options exercised	2,474	0
Net cash (used in) provided by financing activities	(45,264)	187,530
Net (decrease) increase in cash and cash equivalents	(54,584)	12,387
Cash and cash equivalents at beginning of period	187,040	128,032
Cash and cash equivalents at end of period	132,456	140,419
Supplemental Disclosure of Cash Flow Information
Cash paid during the period for interest	15,648	19,391
Cash paid during the period for income taxes	13,660	8,221
Sale and refinancing of other real estate owned	2,507	668
Transfer of loans to other real estate owned	9,889	16,372
Supplemental Disclosure of Non-Cash Investing Activities
Fair value of common stock shares issued	28,290
Cash consideration for outstanding shares	11,025
Fair value of assets acquired	300,541
Liabilities assumed	$ 261,226