CONSOLIDATED STATEMENTS OF CASH FLOW - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Operating activities:
Net income	$ 68,051	$ 57,786	$ 57,486
Adjustments to reconcile net income to net cash provided by operating activities:
Provision for loan and lease losses	8,980	5,833	2,160
Depreciation of premises and equipment	5,658	5,245	4,780
Depreciation of equipment owned and leased to others	25,215	21,678	18,280
Stock-based compensation	2,963	2,884	3,843
Amortization of investment securities premiums and accretion of discounts, net	5,449	5,861	4,652
Amortization of mortgage servicing rights	1,092	1,478	1,424
Deferred income taxes	2,767	2,856	1,620
Gains on investment securities available-for-sale	(4,340)	(1,796)	(4)
Originations of loans held for sale, net of principal collected	(101,104)	(119,134)	(113,029)
Proceeds from the sales of loans held for sale	106,811	116,397	120,138
Net gains on sale of loans held for sale	(2,981)	(3,287)	(3,330)
Net gain on sale of other real estate and repossessions	(251)	(228)	(814)
Change in trading account securities	0	0	205
Change in interest receivable	(2,119)	(1,326)	(549)
Change in interest payable	1,222	570	798
Change in other assets	(1,434)	2,145	(8,230)
Change in other liabilities	(3,268)	648	8,010
Other	4,550	450	3,168
Net change in operating activities	117,261	98,060	100,608
Investing activities:
Proceeds from sales of investment securities available-for-sale	228,715	23,784	1,299
Proceeds from maturities and paydowns of investment securities available-for-sale	177,466	217,613	136,649
Purchases of investment securities available-for-sale	(469,385)	(313,074)	(147,771)
Proceeds from liquidation of partnership investment	128	2,903	423
Net change in other investments	(3,495)	(485)	(1,172)
Loans sold or participated to others	32,004	5,926	1,962
Net change in loans and leases	(382,386)	(209,668)	(315,938)
Net change in equipment owned under operating leases	(46,003)	(30,100)	(54,508)
Purchases of premises and equipment	(5,444)	(8,935)	(9,498)
Proceeds from sales of other real estate and repossessions	6,194	2,189	6,941
Net change in investing activities	(462,206)	(309,847)	(381,613)
Financing activities:
Net change in demand deposits and savings accounts	205,649	278,666	173,508
Net change in time deposits	213,321	(84,092)	162,818
Net change in short-term borrowings	(77,348)	58,714	(12,593)
Proceeds from issuance of long-term debt	19,999	20,837	0
Payments on long-term debt	(26,628)	(6,429)	(1,250)
Stock issued under stock purchase plans	153	120	149
Acquisition of treasury stock	(41)	(8,030)	(9,970)
Cash dividends paid on common stock	(20,431)	(19,416)	(18,126)
Net change in financing activities	314,674	240,370	294,536
Net change in cash and cash equivalents	(30,271)	28,583	13,531
Cash and cash equivalents, beginning of year	108,304	79,721	66,190
Cash and cash equivalents, end of year	78,033	108,304	79,721
Non-cash transactions:
Loans transferred to other real estate and repossessions	8,135	4,961	8,742
Common stock matching contribution to Employee Stock Ownership and Profit Sharing Plan	1,426	800	500
Stock dividend paid on common stock	0	0	90,003
Cash paid for:
Interest	25,531	21,531	17,364
Income taxes	$ 10,567	$ 19,866	$ 30,429