CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Operating Activities
Net income	$ 49,438	$ 38,323	$ 35,542
Adjustments to reconcile net income to net cash provided by operating activities:
Provision for loan losses	1,250	1,705	1,625
Depreciation expense	8,198	7,289	6,410
Amortization of mortgage servicing rights	1,352	1,510	1,313
Recovery of valuation allowance on mortgage servicing rights	(75)		(200)
Securities amortization, net	4,444	4,901	3,386
Amortization of purchased intangible assets	2,011	1,342	1,640
Earnings on cash surrender value of life insurance policies	(1,778)	(1,513)	(1,236)
Gain on life insurance benefit	(431)		(307)
Securities gains, net	(84)	(170)	(386)
Gain on loans sold	(6,467)	(7,311)	(5,553)
Loans originated for sale	(232,027)	(254,581)	(236,928)
Proceeds from loan sales	243,179	256,946	243,230
Stock based compensation expense	1,036	1,145	843
Stock portion of director retainer fee expense	311	382	315
Gain on sale of foreclosed assets	262	268	68
Prepayment penalty on FHLB advance	214		2,364
Tax benefit on stock activity	(528)
Change in other assets and liabilities	(3,863)	(2,665)	1,402
Net cash provided by operating activities	65,918	47,035	53,392
Investing Activities
Net change in short term investments	(105)		(45)
Purchases of securities available for sale	(216,333)	(242,730)	(345,783)
Proceeds from calls, maturities, and payments on securities available for sale	127,224	142,543	136,799
Proceeds from sales of securities available for sale	59,943	88,203	147,109
Loan originations and payments, net	11,628	(144,129)	(176,184)
Purchases of premises and equipment	(4,347)	(14,068)	(7,794)
Proceeds from sale of OREO	3,155	3,985	2,272
Proceeds from redemption of restricted stock	2,483	3,789	2,785
Purchase of restricted stock	(5,168)	(5,531)	(231)
Proceeds from sale of portfolio loans			11,356
Proceeds from life insurance benefit	686		1,094
Cash received/(paid) from business acquisitions, net	2,845	(11,289)	57,083
Net cash used by investing activities	(17,989)	(179,227)	(171,539)
Financing Activities
Net change in deposits	29,861	15,401	83,428
Net change in other borrowings	(86,067)	162,976	2,014
Proceeds from FHLB advances	211,000	420,000	700,000
Repayment of FHLB advances	(168,690)	(451,986)	(647,289)
Proceeds from term debt		30,000
Cash dividends on common stock	(17,162)	(14,296)	(11,680)
Purchase of treasury shares	(395)	(1,045)	(3,527)
Repayment on term debt	(6,666)	(11,667)
Proceeds from exercise of stock options, including tax benefit	1,143	1,783	294
Net cash provided by financing activities	(36,976)	151,166	123,240
Cash and Cash Equivalents, Period Increase (Decrease), Total	10,953	18,974	5,093
Cash and cash equivalents, beginning of period	86,552	67,578	62,485
Cash and cash equivalents, end of period	97,505	86,552	67,578
Supplemental cash flow information
Interest paid	16,418	10,420	8,424
Income taxes paid	8,725	5,365	4,985
Supplemental non cash disclosure
Loan balances transferred to foreclosed real estate	$ 2,917	$ 1,965	1,475
Loan balances transferred to loans held for sale			$ 11,356