CONSOLIDATED STATEMENTS OF INCOME - USD ($) $ in Thousands		12 Months Ended
		Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Interest income:
Loans and leases		$ 168,766	$ 161,215	$ 161,137
Investment securities, taxable		11,929	13,054	14,414
Investment securities, tax-exempt		2,992	3,269	3,094
Other		997	1,016	940
Total interest income		184,684	178,554	179,585
Interest expense:
Deposits		11,489	11,356	16,604
Short-term borrowings		484	541	211
Subordinated notes		4,220	4,220	4,220
Long-term debt and mandatorily redeemable securities		1,970	2,108	1,733
Total interest expense		18,163	18,225	22,768
Net interest income		166,521	160,329	156,817
Provision for loan and lease losses		2,160	3,733	772
Net interest income after provision for loan and lease losses		164,361	156,596	156,045
Noninterest income:
Trust fees		19,126	18,511	17,383
Service charges on deposit accounts		9,313	8,684	9,177
Debit card income		10,217	9,585	8,882
Mortgage banking income		4,570	5,381	5,944
Insurance commissions		5,465	5,556	5,492
Equipment rental income		22,302	17,156	16,229
Gains (losses) on investment securities available-for-sale		4	963	(168)
Other income		12,319	12,051	14,273
Total noninterest income		83,316	77,887	77,212
Noninterest expense:
Salaries and employee benefits		86,133	80,488	79,783
Net occupancy expense		9,768	9,311	8,700
Furniture and equipment expense		18,348	17,657	16,895
Depreciation — leased equipment		18,280	13,893	13,055
Professional fees		4,682	5,046	5,321
Supplies and communication		6,011	5,589	5,690
FDIC and other insurance		3,412	3,384	3,462
Business development and marketing expense		4,837	6,049	4,938
Loan and lease collection and repossession expense		667	1,102	4,030
Other expense		6,976	7,521	7,440
Total noninterest expense		159,114	150,040	149,314
Income before income taxes		88,563	84,443	83,943
Income tax expense		31,077	26,374	28,985
Net income		$ 57,486	$ 58,069	$ 54,958
Basic net income per common share, in dollars per share	[1]	$ 2.17	$ 2.17	$ 2.03
Diluted net income per common share, in dollars per share	[1]	$ 2.17	$ 2.17	$ 2.03

[1] *The computation of basic and diluted net income per common share gives retrospective recognition to a 10% stock dividend declared on July 22, 2015 and issued on August 14, 2015.