Unaudited Condensed Consolidated Statements of Cash Flows - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Operating Activities
Net income	$ 28,682	$ 27,670
Adjustments to reconcile net income to net cash provided by operating activities:
Provision for loan losses	568	765
Net amortization of investment securities premiums and discounts	6,594	6,282
Loans held for sale originated or acquired	(179,471)	(192,332)
Proceeds from sales of loans held for sale	202,605	193,667
Gain on sale of loans	(5,992)	(5,430)
Gain on sale of investments	(108)	(5)
Stock-based compensation expense, net of tax benefits	43	347
Excess tax benefits from stock-based compensation	(20)	(102)
Depreciation of premises and equipment	3,730	3,206
Loss (gain) on sale of other real estate owned and write-downs, net	52	(2)
Amortization of core deposit intangibles	797	731
Net increase in accrued interest receivable	(2,839)	(1,871)
Net decrease in other assets	195	2,619
Net increase (decrease) in accrued interest payable	91	(393)
Net increase in other liabilities	2,803	2,944
Net cash provided by operating activities	57,730	38,096
Investing Activities
Sales of available-for-sale securities	20,539	35,558
Maturities, prepayments and calls of available-for-sale securities	156,779	161,179
Purchases of available-for-sale securities	(163,654)	(311,895)
Maturities, prepayments and calls of held-to-maturity securities	11,155	460
Purchases of held-to-maturity securities	(1,223)	(50,005)
Principal collected on loans	346,124	332,693
Loans originated or acquired	(465,644)	(454,511)
Net addition of premises and equipment and other real estate owned	(2,726)	(3,889)
Proceeds from sale of other real estate owned	4,457	3,245
Net proceeds from sale of non-marketable equity securities	3,297	514
Net cash received in acquisitions	0	19,712
Net cash used in investing activities	(90,896)	(266,939)
Financing Activities
Net increase (decrease) in deposits	71,186	(33,240)
Net increase in securities sold under agreements to repurchase	22,546	27,188
Net decrease in short-term Federal Home Loan Bank advances	(80,000)	0
Repayments of long-term Federal Home Loan Bank advances	(162)	(731)
Net increase (decrease) in other borrowed funds	67	(572)
Cash dividends paid	(22,883)	(22,557)
Excess tax benefits from stock-based compensation	20	102
Stock-based compensation activity	0	(290)
Net cash used in financing activities	(9,226)	(30,100)
Net decrease in cash and cash equivalents	(42,392)	(258,943)
Cash and cash equivalents at beginning of period	193,253	442,409
Cash and cash equivalents at end of period	150,861	183,466
Supplemental Disclosure of Cash Flow Information
Cash paid during the period for interest	7,584	7,775
Cash paid during the period for income taxes	0	0
Supplemental Disclosure of Non-Cash Investing Activities
Sale and refinancing of other real estate owned	474	256
Transfer of loans to other real estate owned	178	3,217
Dividend declared but not paid	15,281	13,631
Fair value of common stock shares issued	0	10,776
Cash consideration for outstanding shares	0	12,219
Fair value of assets acquired	0	174,637
Liabilities assumed	$ 0	$ 152,779