Consolidated Statements of Income and Comprehensive Income - USD ($) shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Interest income:
Interest and fees on loans, including loans held for sale	$ 130,829	$ 128,457	$ 131,725
Interest and dividends on securities:
Taxable	9,153	11,314	12,425
Tax exempt	2,705	2,576	2,249
Interest and dividends on Federal Reserve Bank and Federal Home Loan Bank stock	1,010	1,136	1,367
Other, including interest on federal funds sold	323	384	361
Total interest income	144,020	143,867	148,127
Interest expense:
Interest on deposits	9,616	9,798	11,313
Interest on repurchase agreements and other short-term borrowings	938	841	940
Interest on advances from Federal Home Loan Bank	49	27	26
Interest on long-term debt	1,170	1,131	1,161
Total interest expense	11,773	11,797	13,440
Net interest income	132,247	132,070	134,687
Provision for loan losses	8,650	8,755	8,568
Net interest income after provision for loan losses	123,597	123,315	126,119
Noninterest income:
Service charges on deposit accounts	24,282	23,892	24,650
Gains on sales of loans, net	1,978	1,468	3,098
Trust and wealth management income	9,286	9,011	8,199
Loan related fees	3,821	3,531	4,697
Bank owned life insurance	2,158	1,996	2,747
Brokerage revenue	1,426	2,454	2,245
Securities losses	(106)	(211)	(45)
Other noninterest income	3,964	2,940	3,713
Total noninterest income	46,809	45,081	49,304
Noninterest expense:
Officer salaries and employee benefits	11,652	11,076	10,432
Other salaries and employee benefits	42,911	43,417	42,411
Occupancy, net	7,826	8,017	7,804
Equipment	3,049	3,414	3,865
Data processing	6,743	7,877	7,308
Bank franchise tax	5,174	4,857	4,493
Legal fees	2,236	2,444	2,392
Professional fees	1,884	1,832	1,790
FDIC insurance	2,382	2,400	2,442
Other real estate owned provision and expense	3,533	3,897	5,154
Repossession expense	1,265	1,508	1,522
Amortization of limited partnership investments	2,580	859	729
Other noninterest expense	14,208	14,401	19,909
Total noninterest expense	105,443	105,999	110,251
Income before income taxes	64,963	62,397	65,172
Income taxes	18,531	19,146	20,000
Net income	46,432	43,251	45,172
Unrealized holding gains (losses) on securities available-for-sale:
Unrealized holding gains (losses) arising during the period	(342)	13,928	(31,878)
Less: Reclassification adjustments for realized losses included in net income	(106)	(211)	(45)
Tax (benefit) expense	(83)	4,949	(11,142)
Other comprehensive income (loss), net of tax	(153)	9,190	(20,691)
Comprehensive income	$ 46,279	$ 52,441	$ 24,481
Basic earnings per share (in dollars per share)	$ 2.66	$ 2.50	$ 2.63
Diluted earnings per share (in dollars per share)	$ 2.66	$ 2.49	$ 2.62
Weighted average shares outstanding-basic (in shares)	17,431	17,326	17,158
Weighted average shares outstanding-diluted (in shares)	17,483	17,397	17,240
Dividends declared per share (in dollars per share)	$ 1.220	$ 1.181	$ 1.154