CONSOLIDATED STATEMENTS OF INCOME - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Interest income:
Loans and leases	$ 194,726	$ 175,999	$ 168,766
Investment securities, taxable	13,693	11,777	11,929
Investment securities, tax-exempt	2,573	2,740	2,992
Other	1,393	1,244	997
Total interest income	212,385	191,760	184,684
Interest expense:
Deposits	19,202	15,267	11,489
Short-term borrowings	1,115	525	484
Subordinated notes	4,002	4,220	4,220
Long-term debt and mandatorily redeemable securities	2,435	2,089	1,970
Total interest expense	26,754	22,101	18,163
Net interest income	185,631	169,659	166,521
Provision for loan and lease losses	8,980	5,833	2,160
Net interest income after provision for loan and lease losses	176,651	163,826	164,361
Noninterest income:
Trust and wealth advisory	20,980	19,256	19,126
Service charges on deposit accounts	9,564	9,053	9,313
Debit card	11,809	10,887	10,217
Mortgage banking	4,796	4,496	4,570
Insurance commissions	5,889	5,513	5,465
Equipment rental	30,381	25,863	22,302
Gains on investment securities available-for-sale	4,340	1,796	4
Other	10,947	12,081	12,319
Total noninterest income	98,706	88,945	83,316
Noninterest expense:
Salaries and employee benefits	86,912	86,837	86,133
Net occupancy	10,624	9,686	9,768
Furniture and equipment	20,769	19,500	18,348
Depreciation — leased equipment	25,215	21,678	18,280
Professional fees	6,810	5,161	4,682
Supplies and communication	5,355	5,244	6,011
FDIC and other insurance	2,537	3,147	3,412
Business development and marketing	7,477	4,936	4,837
Loan and lease collection and repossession	2,724	1,600	667
Other	5,574	5,856	6,976
Total noninterest expense	173,997	163,645	159,114
Income before income taxes	101,360	89,126	88,563
Income tax expense	33,309	31,340	31,077
Net income	$ 68,051	$ 57,786	$ 57,486
Basic net income per common share, in dollars per share	$ 2.60	$ 2.22	$ 2.17
Diluted net income per common share, in dollars per share	$ 2.60	$ 2.22	$ 2.17