CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Operating activities:
Net income	$ 168,641	$ 150,717	$ 103,812
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation	15,749	16,024	14,398
Amortization of intangible assets	18,155	16,941	5,479
Net accretion on securities, loans and borrowings	(9,404)	(6,619)	(4,405)
Stock-based compensation	6,064	5,137	4,783
Provision for loan losses	10,837	10,984	8,076
Provision/(benefit) for deferred income taxes	2,663	(28,692)	13,066
Amortization of mortgage servicing rights	449	499	518
Unrealized gain on equity securities	(657)	0	0
Loss on debt extinguishment	318	0	0
Income from bank-owned life insurance policies	(1,579)	(1,586)	(1,505)
Gain on sales of investment securities, net	0	(2)	0
Net (gain)/loss on sale of loans and other assets	(80)	181	(837)
Change in other assets and liabilities	10,252	26,090	(7,614)
Net cash provided by operating activities	221,408	189,674	135,771
Investing activities:
Proceeds from maturities, calls and paydowns of available-for-sale investment securities	140,784	157,278	109,638
Proceeds from maturities and redemptions of other investment securities	5,867	30,116	8,703
Purchases of available-for-sale investment securities	(78,131)	(90,380)	(65,966)
Purchases of equity and other securities	(31)	(13,302)	(4,612)
Net (increase) decrease in loans	(35,414)	164,846	(159,871)
Cash paid for acquisition, net of cash acquired of $16, $52,132, and $0, respectively	(1,737)	(107,414)	(575)
Settlement of bank-owned life insurance policies	0	1,779	3,127
Purchases of premises and equipment, net	(12,646)	(10,819)	(12,442)
Real estate limited partnership investments	(1,197)	(733)	0
Net cash provided by/(used in) investing activities	17,495	131,371	(121,998)
Financing activities:
Net change in deposits	(122,049)	(79,940)	202,480
Net decrease in borrowings, net of payments of $95, $81,544 and $0	(47,339)	(144,809)	(155,100)
Payments on subordinated debt held by unconsolidated subsidiary trusts	(25,207)	0	0
Issuance of common stock	6,443	4,563	10,543
Purchase of treasury stock	(298)	(3,306)	(3,470)
Sale of treasury stock	12,561	10,060	8,888
Increase in deferred compensation arrangements	298	3,306	0
Cash dividends paid	(71,495)	(62,305)	(55,048)
Withholding taxes paid on share-based compensation	(1,021)	(1,433)	(1,419)
Net cash (used in)/provided by financing activities	(248,107)	(273,864)	6,874
Change in cash and cash equivalents	(9,204)	47,181	20,647
Cash and cash equivalents at beginning of year	221,038	173,857	153,210
Cash and cash equivalents at end of year	211,834	221,038	173,857
Supplemental disclosures of cash flow information:
Cash paid for interest	17,926	13,705	11,268
Cash paid for income taxes	30,266	41,231	32,239
Supplemental disclosures of noncash financing and investing activities:
Dividends declared and unpaid	19,808	17,460	14,268
Transfers from loans to other real estate	3,299	3,518	2,612
Acquisitions:
Common stock issued	0	343,132	0
Fair value of assets acquired, excluding acquired cash and intangibles	115	1,961,246	0
Fair value of liabilities assumed	$ 31	$ 1,870,449	$ 0