Consolidated Statements of Comprehensive Income - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
INTEREST INCOME
Loans, including fees	$ 190,292	$ 182,972	$ 167,051
Securities:
Taxable	5,492	5,727	4,947
Tax-exempt	982	1,061	1,222
Federal funds sold	14	2	2
Interest-bearing deposits with banks	4,265	4,391	4,064
Total interest income	201,045	194,153	177,286
INTEREST EXPENSE
Deposits	10,251	10,795	11,579
Short-term borrowings	4	16	6
Long-term borrowings	32	25	216
Junior subordinated debentures	1,966	1,966	1,966
Total interest expense	12,253	12,802	13,767
Net interest income	188,792	181,351	163,519
Provision for loan losses	7,675	3,072	1,258
Net interest income after provision for loan losses	181,117	178,279	162,261
NONINTEREST INCOME
Trust revenue	9,091	9,180	8,072
Service charges on deposits	57,651	56,389	52,450
Securities transactions (includes accumulated other comprehensive income reclassifications of $3,814, $533 and $137, respectively)	9,269	1,641	420
Income from sales of loans	1,968	1,813	2,306
Insurance commissions	14,791	14,642	14,094
Cash management	7,510	6,741	6,250
Gain on sale of other assets	79	335	293
Other	5,449	5,672	6,270
Total noninterest income	105,808	96,413	90,155
NONINTEREST EXPENSE
Salaries and employee benefits	113,083	108,640	102,165
Occupancy, net	11,512	11,610	10,635
Depreciation	9,966	9,595	9,412
Amortization of intangible assets	1,935	1,754	1,665
Data processing services	4,579	4,689	4,785
Net expense from other real estate owned	324	511	434
Marketing and business promotion	6,986	7,024	6,652
Deposit insurance	3,358	3,291	3,003
Other	33,972	36,407	32,823
Total noninterest expense	185,715	183,521	171,574
Income before taxes	101,210	91,171	80,842
Income tax expense	35,040	27,284	26,525
Net income	$ 66,170	$ 63,887	$ 54,317
NET INCOME PER COMMON SHARE
Basic	$ 4.25	$ 4.14	$ 3.56
Diluted	$ 4.17	$ 4.04	$ 3.49
OTHER COMPREHENSIVE INCOME
Unrealized gains (losses) on securities, net of tax of $207, $(747) and $1,249, respectively	$ (327)	$ 613	$ (2,321)
Reclassification adjustment for gains included in net income, net of tax of $1,475, $206 and $48, respectively	(2,339)	(327)	(89)
Other comprehensive gain (loss), net of tax of $1,682, $(541) and $1,297, respectively	(2,666)	286	(2,410)
Comprehensive income	$ 63,504	$ 64,173	$ 51,907