Consolidated Statements of Income - USD ($) shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Interest and Loan Fee Income:
Loans	$ 61,740	$ 69,139	$ 78,441
Investment securities available for sale	44,664	34,276	31,263
Investment securities held to maturity	27,432	30,636	26,825
Total Interest and Loan Fee Income	133,836	134,051	136,529
Interest Expense:
Deposits	1,856	2,077	2,370
Short-term borrowed funds	44	39	53
Federal Home Loan Bank advances			1
Total Interest Expense	1,900	2,116	2,424
Net Interest and Loan Fee Income	131,936	131,935	134,105
(Reversal of) provision for loan losses	(1,900)	(3,200)
Net Interest and Loan Fee Income After Reversal of Provision For Loan Losses	133,836	135,135	134,105
Noninterest Income:
Service charges on deposit accounts	19,612	20,854	22,241
Merchant processing services	8,426	6,377	6,339
Securities gains	7,955
Debit card fees	6,421	6,290	6,084
Trust fees	2,875	2,686	2,732
ATM processing fees	2,610	2,411	2,397
Other service fees	2,584	2,571	2,689
Financial services commissions	639	568	695
Other noninterest income	5,506	4,817	4,690
Total Noninterest Income	56,628	46,574	47,867
Noninterest Expense:
Salaries and related benefits	51,519	51,507	52,192
Occupancy and equipment	19,430	19,017	19,394
Outsourced data processing services	9,035	8,505	8,441
Loss contingency	5,542	3
Amortization of identifiable intangibles	3,077	3,504	3,856
Professional fees	2,161	3,980	2,490
Courier service	1,732	1,952	2,329
Impairment of tax credit investments	625
Other noninterest expense	10,171	13,284	16,598
Total Noninterest Expense	103,292	101,752	105,300
Income Before Income Taxes	87,172	79,957	76,672
Provision for income taxes	37,147	21,104	17,919
Net Income	$ 50,025	$ 58,853	$ 58,753
Average Common Shares Outstanding (in shares)	26,291	25,612	25,555
Diluted Average Common Shares Outstanding (in shares)	26,419	25,678	25,577
Per Common Share Data:
Basic earnings (in dollars per share)	$ 1.90	$ 2.30	$ 2.30
Diluted earnings (in dollars per share)	1.89	2.29	2.30
Dividends paid (in dollars per share)	$ 1.57	$ 1.56	$ 1.53