CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Operating activities:
Net income	$ 103,812	$ 91,230	$ 91,353
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation	14,398	13,132	13,082
Amortization of intangible assets	5,479	3,663	4,287
Net (accretion)/amortization on securities, loans and borrowings	(4,405)	(3,289)	(3,533)
Stock-based compensation	4,783	4,201	3,993
Provision for loan losses	8,076	6,447	7,178
Provision for deferred income taxes	13,066	10,716	7,461
Amortization of mortgage servicing rights	518	409	444
Income from bank-owned life insurance policies	(1,505)	(1,086)	(1,037)
Loss on sales of investment securities, net	0	4	0
Net gain on sale of loans and other assets	(837)	(180)	(154)
Change in other assets and liabilities	(12,124)	(8,784)	(970)
Net cash provided by operating activities	131,261	116,463	122,104
Investing activities:
Proceeds from sales of available-for-sale investment securities	0	221,136	0
Proceeds from maturities of available-for-sale investment securities	109,638	169,562	137,282
Proceeds from maturities of other securities	8,703	1,790	13
Purchases of available-for-sale investment securities	(65,966)	(503,000)	(310,517)
Purchases of other securities	(4,612)	0	(7,500)
Net change in loans	(159,871)	(176,754)	(137,207)
Cash received/(paid) for acquisitions, net of cash acquired of $0, $81,772, and $0, respectively	(575)	25,505	(924)
Settlement of bank-owned life insurance policies	3,127	0	1,097
Purchases of premises and equipment, net	(12,442)	(12,400)	(13,376)
Net cash (used in) provided by investing activities	(121,998)	(274,161)	(331,132)
Financing activities:
Net increase in deposits	202,480	238,969	39,220
Net change in borrowings, net of payments of $0, $0 and $13	(155,100)	(36,700)	196,087
Issuance of common stock	10,543	9,774	9,417
Purchases of treasury stock	(3,470)	(9,126)	(4,368)
Sale of treasury stock	8,888	16,571	1,531
Cash dividends paid	(55,048)	(49,273)	(46,178)
Tax benefits from share-based payment arrangements	3,091	2,297	2,068
Net cash provided by (used in) financing activities	11,384	172,512	197,777
Change in cash and cash equivalents	20,647	14,814	(11,251)
Cash and cash equivalents at beginning of year	153,210	138,396	149,647
Cash and cash equivalents at end of year	173,857	153,210	138,396
Supplemental disclosures of cash flow information:
Cash paid for interest	11,268	11,252	11,937
Cash paid for income taxes	32,239	28,891	29,457
Supplemental disclosures of noncash financing and investing activities:
Dividends declared and unpaid	14,268	13,605	12,254
Transfers from loans to other real estate	2,612	3,943	2,546
Acquisitions:
Common stock issued	0	102,202	0
Fair value of assets acquired, excluding acquired cash and intangibles	0	675,025	64
Fair value of liabilities assumed	$ 0	$ 700,574	$ 0