Consolidated Statements of Income - USD ($)	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Interest income
Interest and fees on loans	$ 224,244,000	$ 214,724,000	$ 197,021,000
Taxable interest and dividends on securities	20,851,000	20,120,000	18,610,000
Nontaxable interest and dividends on securities	117,000	127,000	144,000
Interest on loans held for sale	235,000	225,000	405,000
Interest on federal funds sold and short-term investments	1,190,000	349,000	279,000
Total interest and dividend income	246,637,000	235,545,000	216,459,000
Interest expense
Interest on deposits	11,140,000	11,576,000	11,039,000
Interest on borrowings	7,653,000	9,041,000	9,378,000
Total interest expense	18,793,000	20,617,000	20,417,000
Net interest income	227,844,000	214,928,000	196,042,000
Provision (benefit)	6,075,000	1,500,000	10,403,000
Net interest income after provision for loan losses	221,769,000	213,428,000	185,639,000
Noninterest income
Deposit account fees	18,085,000	18,078,000	18,065,000
Interchange and ATM fees	16,210,000	14,728,000	12,975,000
Investment management	21,809,000	20,735,000	19,642,000
Fees and Commission Mortgage Banking	6,607,000	5,163,000	3,384,000
Increase in cash surrender value of life insurance policies	4,089,000	3,692,000	3,128,000
Gain on life insurance benefits	0	0	1,964,000
Available-For-Sale Securities - Fixed Income Gross Realized Gains	0	798,000	121,000
Gain (Loss) on Sale of Equity Investments	6,000	20,000	91,000
Loan level derivative income	6,155,000	3,830,000	2,477,000
Other noninterest income	9,467,000	8,844,000	8,096,000
Total noninterest income	82,428,000	75,888,000	69,943,000
Noninterest expenses
Salaries and employee benefits	108,636,000	105,068,000	94,044,000
Occupancy and equipment expenses	22,867,000	23,020,000	21,820,000
Data processing & facilities management	4,975,000	4,631,000	4,765,000
FDIC assessment	3,380,000	3,979,000	3,770,000
Advertising expense	5,202,000	4,645,000	3,859,000
Consulting expense	3,486,000	3,680,000	2,923,000
Gains (Losses) on Extinguishment of Debt	437,000	122,000	0
Available-for-Sale Securities - Fixed Income Gross Realized Losses	0	1,124,000	21,000
Available-For-Sale Securities - Equity Gross Realized Losses	32,000	99,000	0
Merger and acquisition expense	5,455,000	10,501,000	1,339,000
Other noninterest expenses	37,652,000	40,269,000	39,297,000
Total noninterest expenses	192,122,000	197,138,000	171,838,000
Income before income taxes	112,075,000	92,178,000	83,744,000
Provision for income taxes	35,427,000	27,218,000	23,899,000
Net Income	$ 76,648,000	$ 64,960,000	$ 59,845,000
Basic earnings per share (in dollars per share)	$ 2.90	$ 2.51	$ 2.50
Diluted earnings per share (in dollars per share)	$ 2.90	$ 2.50	$ 2.49
Weighted average common shares (basic) (in shares)	26,404,071	25,891,382	23,899,562
Common share equivalents (in shares)	51,847	68,566	93,815
Weighted average common shares (diluted) (in shares)	26,455,918	25,959,948	23,993,377.000
Retained Earnings
Noninterest expenses
Net Income	$ 76,648,000	$ 64,960,000	$ 59,845,000
Cash dividends declared (in dollars per share)	$ 1.16	$ 1.04	$ 0.96