Consolidated Statements of Cash Flows (Unaudited) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016
Cash flows from operating activities:
Net income	$ 44,994	$ 45,678
Adjustments to reconcile net income to net cash provided by operating activities:
Provision for loan losses	4,085	6,550
Net (gain) loss on disposal of property and equipment	76	188
Depreciation and amortization	9,665	9,491
Net premium amortization on investment securities	5,710	6,347
Net gains on investment securities transactions	(7)	(87)
Net gains on sales of mortgage loans held for sale	(9,898)	(10,544)
Net gain on sale of OREO	(217)	(636)
Write-downs of OREO and other assets pending disposal	60	621
Net Gain on Health Savings Accounts	(3,431)	0
Net reversal of impairment of mortgage servicing rights	(72)	(5)
Deferred income tax expense	(15,828)	321
Net increase in cash surrender value of company-owned life insurance policies	(2,587)	(2,271)
Stock-based compensation expense	2,468	2,385
Tax benefits from stock-based compensation expense	0	619
Excess tax benefits from stock-based compensation	0	(495)
Originations of loans held for sale	(428,286)	(468,560)
Proceeds from sales of loans held for sale	478,239	457,132
Changes in operating assets and liabilities:
Increase in interest receivable	(5,978)	281
Increase in other assets	26,231	(14,551)
Decrease in accrued interest payable	3,496	687
Decrease in accounts payable and accrued expenses	(20,170)	3,701
Net cash provided by operating activities	88,550	36,852
Cash flows from investing activities:
Purchases of held-to-maturity investment securities	(2,948)	(9,883)
Purchases of available-for-sale investment securities	(201,806)	(459,569)
Proceeds from maturities and paydowns of held-to-maturity investment securities	43,545	53,977
Proceeds from maturities and paydowns of available-for-sale investment securities	170,237	424,458
Purchases of company-owned life insurance	0	0
Extensions of credit to customers, net of repayments	(38,468)	(159,410)
Recoveries of loans charged-off	3,566	4,717
Proceeds from sales of OREO	1,712	2,398
Acquisition of intangible assets	28,013	0
Proceeds from the sale of Health Savings Accounts	6,500	0
Proceeds from sale of loan production office	0	932
Acquisition of bank and bank holding company, net of cash and cash equivalents received	91,775	0
Capital expenditures, net of sales	(7,548)	(3,638)
Net cash used in investing activities	38,552	(146,018)
Cash flows from financing activities:
Net increase (decrease) in deposits	(25,086)	(107,489)
Net increase (decrease) in repurchase agreements	42,216	(44,236)
Net increase (decrease) in other borrowed funds	15,013	13
Repayments of long-term debt	(34)	(32)
Advances on long-term debt	81	75
Proceeds from issuance of common stock	902	1,684
Excess tax benefits from stock-based compensation	0	495
Purchase and retirement of common stock	(891)	(26,042)
Dividends paid to common stockholders	(21,551)	(19,708)
Net cash provided by (used in) financing activities	10,650	(195,240)
Net increase (decrease) in cash and cash equivalents	137,752	(304,406)
Cash and cash equivalents at beginning of period	782,023	780,457
Cash and cash equivalents at end of period	919,775	476,051
Supplemental disclosures of cash flow information:
Cash paid during the period for income taxes	14,379	27,566
Cash paid during the period for interest expense	8,614	8,069
Transfer of loans to loans held for sale	5,805	26
Transfer of loans to other real estate owned	1,554	4,019
Capitalization of internally originated mortgage servicing rights	2,727	1,768
Investment securities available for sale	424,302	0
oncash or Part Noncash Acquisition, HTM Investments Acquired	57,307	0
Noncash or Part Noncash Acquisition, Loans Held for Sale Acquired	10,253	0
Noncash or Part Noncash Acquisition, Loans Acquired	2,080,083	0
Noncash or Part Noncash Acquisition, Fixed Assets Acquired	47,869	0
Noncash or Part Noncash Acquisition, Goodwill	231,507
Noncash or Part Noncash Acquisition, Value of Assets Acquired	3,025,728	0
Noncash or Part Noncash Acquisition, Intangible Assets Acquired	47,950	0
Noncash or Part Noncash Acquisition, Mortgage Servicing Asset Acquired	3,491	0
Noncash or Part Noncash Acquisition, Other Real Estate Owned Acquired	1,268	0
Noncash or Part Noncash Acquisition, Other Assets Acquired	121,698	0
Noncash or Part Noncash Acquisition, Deposits Acquired	2,668,976	0
Noncash or Part Noncash Acquisition, Payables Assumed	62,558	0
Noncash or Part Noncash Acquisition, Value of Liabilities Assumed	$ 2,731,534	$ 0