Unaudited Condensed Consolidated Statements of Cash Flows - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014
Operating Activities
Net income	$ 86,619	$ 84,701
Adjustments to reconcile net income to net cash provided by operating activities:
Provision for loan losses	1,873	1,721
Net amortization of investment securities premiums and discounts	20,082	21,239
Loans held for sale originated or acquired	(681,826)	(498,118)
Proceeds from sales of loans held for sale	719,989	504,518
Gain on sale of loans	(20,356)	(14,373)
Loss on sale of investments	124	160
Bargain purchase gain	0	(680)
Stock-based compensation expense, net of tax benefits	737	652
Excess tax (benefits) deficiencies from stock-based compensation	(102)	14
Depreciation of premises and equipment	10,178	8,706
Loss (gain) on sale of other real estate owned and write-downs, net	997	(1,096)
Amortization of core deposit intangibles	2,206	2,095
Net (increase) decrease in accrued interest receivable	(5,397)	254
Net increase in other assets	(7,198)	(1,373)
Net decrease in accrued interest payable	(645)	(530)
Net increase in other liabilities	6,547	12,908
Net cash provided by operating activities	133,828	120,798
Investing Activities
Sales of available-for-sale securities	52,691	162,930
Maturities, prepayments and calls of available-for-sale securities	504,062	476,286
Purchases of available-for-sale securities	(686,146)	(126,666)
Maturities, prepayments and calls of held-to-maturity securities	16,762	8,930
Purchases of held-to-maturity securities	(148,583)	(11,250)
Principal collected on loans	1,202,256	993,806
Loans originated or acquired	(1,524,814)	(1,273,235)
Net addition of premises and equipment and other real estate owned	(10,099)	(9,463)
Proceeds from sale of other real estate owned	7,769	12,644
Net proceeds from sale of non-marketable equity securities	29,886	801
Net cash received (paid) in acquisitions	19,712	(2,112)
Net cash (used in) provided by investing activities	(536,504)	232,671
Financing Activities
Net increase in deposits	181,147	217,203
Net increase in securities sold under agreements to repurchase	42,578	53,819
Net decrease in short-term Federal Home Loan Bank advances	0	(381,000)
Proceeds from long-term Federal Home Loan Bank advances	50,000	175,000
Repayments of long-term Federal Home Loan Bank advances	(19,581)	(267,316)
Net decrease in other borrowed funds	(585)	(929)
Cash dividends paid	(50,576)	(24,629)
Excess tax benefits (deficiencies) from stock-based compensation	102	(14)
Stock-based compensation activity	17	837
Net cash provided by (used in) financing activities	203,102	(227,029)
Net (decrease) increase in cash and cash equivalents	(199,574)	126,440
Cash and cash equivalents at beginning of period	442,409	155,657
Cash and cash equivalents at end of period	242,835	282,097
Supplemental Disclosure of Cash Flow Information
Cash paid during the period for interest	22,705	20,128
Cash paid during the period for income taxes	33,912	23,504
Supplemental Disclosure of Non-Cash Investing Activities
Transfer of investment securities from available-for-sale to held-to-maturity	0	484,583
Sale and refinancing of other real estate owned	382	665
Transfer of loans to other real estate owned	6,910	8,995
Fair value of common stock shares issued	10,776	15,127
Cash consideration for outstanding shares	12,219	16,690
Fair value of assets acquired	174,637	349,167
Liabilities assumed	$ 152,779	$ 316,670