Condensed Consolidated Statements of Cash Flows (Unaudited) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016
Cash Flows from Operating Activities
Interest and dividends received	$ 223,172	$ 208,995
Service charges and other fees received	26,769	23,185
Interest paid	(6,279)	(6,089)
Net cash paid to vendors, employees and others	(82,411)	(95,870)
Income taxes	(53,278)	(31,495)
Payments to FDIC, loss share agreement	(498)	(510)
Net cash provided by operating activities	107,475	98,216
Cash Flows from Investing Activities
Proceeds from redemption of FHLB stock	1,952	1,423
Net change in interest-earning balances from depository institutions	27,806	11,849
Proceeds from sale of investment securities held-for-sale	5,403	1,957
Proceeds from repayment of investment securities available-for-sale	320,599	325,912
Proceeds from maturity of investment securities available-for-sale	20,937	81,209
Purchases of investment securities available-for-sale	(280,365)	(208,563)
Proceeds from repayment and maturity of investment securities held-to-maturity	96,447	231,355
Purchases of investment securities held-to-maturity	(36,166)	(261,457)
Net increase in loan and lease finance receivables	(29,713)	(109,046)
Proceeds from sale of loans	0	6,417
Proceeds from sale of asset held-for-sale	4,012	0
Purchase of premises and equipment	(3,129)	(2,343)
Proceeds from sales of other real estate owned	0	1,846
Cash used in sale of branch, net	0	(8,217)
Cash acquired from acquisition, net of cash paid	28,325	(7,504)
Net cash provided by investing activities	156,108	64,838
Cash Flows from Financing Activities
Net (decrease) increase in other deposits	(23,896)	508,916
Net decrease in time deposits	(39,485)	(319,877)
Repayment of FHLB advances	0	(5,000)
Net increase (decrease) in other borrowings	10,000	(46,000)
Net decrease in customer repurchase agreements	(147,959)	(112,293)
Cash dividends on common stock	(41,626)	(38,652)
Repurchase of common stock	(997)	(496)
Proceeds from exercise of stock options	2,537	3,174
Tax benefit related to exercise of stock options	0	236
Net cash used in financing activities	(241,426)	(9,992)
Net increase in cash and cash equivalents	22,157	153,062
Cash and cash equivalents, beginning of period	121,633	106,097
Cash and cash equivalents, end of period	143,790	259,159
Reconciliation of Net Earnings to Net Cash Provided by Operating Activities
Net earnings	86,560	74,353
Adjustments to reconcile net earnings to net cash provided by operating activities:
Gain on sale of loans	0	(1,101)
Gain on sale of branch	0	(272)
Gain on sale of investment securities	(402)	(548)
Gain on sale of other real estate owned	0	(30)
Increase in bank owned life insurance	(1,763)	(3,117)
Net amortization of premiums and discounts on investment securities	13,585	15,422
Accretion of PCI discount	(756)	(2,112)
Recapture of provision for loan losses	(7,000)	(2,000)
Valuation adjustment on other real estate owned	0	337
Payments to FDIC, loss share agreement	(498)	(510)
Stock-based compensation	2,200	2,154
Depreciation and amortization, net	(433)	3,128
Change in other assets and liabilities	15,982	12,512
Total adjustments	20,915	23,863
Net cash provided by operating activities	107,475	98,216
Supplemental Disclosure of Non-cash Investing Activities
Securities purchased and not settled	1,625	43,111
Issuance of common stock for acquisition	$ 37,637	$ 21,642