Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Operating activities
Net income	$ 78,409	$ 76,425	$ 75,074
Adjustments to reconcile net income to net cash provided by operating activities
Provision for loan losses	25,431	18,285	19,539
Depreciation and amortization of premises and equipment	9,023	8,646	8,324
Net accretion on securities	5,278	2,554	3,216
Amortization of intangible assets	3,928	4,864	5,047
Stock based compensation	4,378	4,086	3,521
Bank owned life insurance income	(5,195)	(4,334)	(5,349)
Trading security purchases	(287)	(810)	(1,626)
(Gains) losses in trading securities	(594)	226	(388)
Proceeds from sale of loans held for sale	96,603	72,498	7,050
Originations and purchases of loans held for sale	(96,692)	(69,677)	(10,215)
Net gains on sales of loans held for sale	(499)	(239)	(17)
Net security losses (gains)	644	(3,087)	(92)
Net gains on sales of other real estate owned	(687)	(1,337)	(459)
Gain on sale of equity investment	0	(4,179)	(19,401)
Gain on asset sold	(2,462)	0	0
Impairment write-down	2,565	0	0
Prepayment penalties on long-term debt	0	0	17,902
Net decrease (increase) in other assets	364	15,386	(19,601)
Net (decrease) increase in other liabilities	(10,697)	5,236	5,286
Net cash provided by operating activities	109,510	124,543	87,811
Investing activities
Net cash (used in) acquisitions	(2,000)	(3,100)	0
Securities available for sale:
Proceeds from maturities, calls, and principal paydowns	324,781	299,302	236,133
Proceeds from sales	98,466	15,091	189
Purchases	(597,428)	(481,262)	(197,652)
Securities held to maturity:
Proceeds from maturities, calls, and principal paydowns	100,893	79,212	44,756
Purchases	(157,418)	(95,272)	(49,479)
Other:
Net increase in loans	(344,448)	(315,363)	(212,238)
Proceeds from FHLB stock redemption	158,818	60,852	78,441
Purchases of Federal Reserve and FHLB stock	(169,178)	(64,899)	(64,203)
Proceeds from settlement of bank owned life insurance	1,477	1,541	6,064
Purchase of bank owned life insurance	(47,250)	0	0
Purchases of premises and equipment, net	(3,308)	(8,193)	(9,003)
Proceeds from sales of equity investment	0	4,179	19,639
Proceeds from sales of other real estate owned	6,635	3,908	3,612
Net cash used in investing activities	(629,960)	(504,004)	(143,741)
Financing activities
Net increase in deposits	368,845	305,238	409,381
Net increase (decrease) in short-term borrowings	239,222	125,679	(139,240)
Proceeds from issuance of long-term debt	23,880	0	120,051
Repayments of long-term debt	(50,240)	(498)	(315,831)
Proceeds from the issuance of shares to employee benefit plans and other stock plans	3,700	7,649	6,256
Purchase of treasury stock	(17,193)	(26,797)	(72)
Cash dividends	(38,880)	(38,149)	(36,905)
Net cash provided by financing activities	529,334	373,122	43,640
Net increase (decrease) in cash and cash equivalents	8,884	(6,339)	(12,290)
Cash and cash equivalents at beginning of year	140,297	146,636	158,926
Cash and cash equivalents at end of year	149,181	140,297	146,636
Cash paid during the period for:
Interest	22,466	20,908	23,387
Income taxes, net of refund	40,879	28,684	38,912
Noncash investing activities:
Loans transferred to other real estate owned	6,863	3,293	4,330
Preferred stock acquired from sale of equity investment	0	0	2,762
Transfer of available for sale securities to held to maturity portfolio	0	0	332,115
Acquisitions:
Fair value of assets acquired	$ 2,584	$ 4,100	$ 0