Consolidated Statements of Income - USD ($)	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Interest income
Interest and fees on loans	$ 214,724,000	$ 197,021,000	$ 189,748,000
Taxable interest and dividends on securities	20,120,000	18,610,000	15,137,000
Nontaxable interest and dividends on securities	127,000	144,000	55,000
Interest on loans held for sale	225,000	405,000	774,000
Interest on federal funds sold and short-term investments	349,000	279,000	200,000
Total interest and dividend income	235,545,000	216,459,000	205,914,000
Interest expense
Interest on deposits	11,576,000	11,039,000	10,624,000
Interest on borrowings	9,041,000	9,378,000	12,712,000
Total interest expense	20,617,000	20,417,000	23,336,000
Net interest income	214,928,000	196,042,000	182,578,000
Provision (benefit)	1,500,000	10,403,000	10,200,000
Net interest income after provision for loan losses	213,428,000	185,639,000	172,378,000
Noninterest income
Deposit account fees	18,078,000	18,065,000	17,940,000
Interchange and ATM fees	14,728,000	12,975,000	10,883,000
Investment management	20,735,000	19,642,000	16,832,000
Fees and Commission Mortgage Banking	5,163,000	3,384,000	6,734,000
Increase in cash surrender value of life insurance policies	3,692,000	3,128,000	3,229,000
Gain on life insurance benefits	0	1,964,000	227,000
Gains (Losses) on Extinguishment of Debt	0	0	763,000
Available-For-Sale Securities - Fixed Income Gross Realized Gains	798,000	121,000	258,000
Gain (Loss) on Sale of Equity Investments	20,000	91,000	(28,000)
Loan level derivative income	3,830,000	2,477,000	3,439,000
Other noninterest income	8,844,000	8,096,000	7,732,000
Total noninterest income	75,888,000	69,943,000	68,009,000
Noninterest expenses
Salaries and employee benefits	105,068,000	94,044,000	89,894,000
Occupancy and equipment expenses	23,020,000	21,820,000	19,650,000
Data processing & facilities management	4,631,000	4,765,000	4,748,000
FDIC assessment	3,979,000	3,770,000	3,579,000
Advertising expense	4,645,000	3,859,000	4,280,000
Consulting expense	3,680,000	2,923,000	3,322,000
Debit Card	2,456,000	2,362,000	2,994,000
Available-for-Sale Securities - Fixed Income Gross Realized Losses	1,124,000	21,000	0
Available-For-Sale Securities - Equity Gross Realized Losses	99,000	0	0
Merger and acquisition expense	10,501,000	1,339,000	8,685,000
Other noninterest expenses	37,935,000	36,935,000	36,497,000
Total noninterest expenses	197,138,000	171,838,000	173,649,000
Income before income taxes	92,178,000	83,744,000	66,738,000
Provision for income taxes	27,218,000	23,899,000	16,484,000
Net Income	$ 64,960,000	$ 59,845,000	$ 50,254,000
Basic earnings per share (in dollars per share)	$ 2.51	$ 2.50	$ 2.18
Diluted earnings per share (in dollars per share)	$ 2.50	$ 2.49	$ 2.18
Weighted average common shares (basic) (in shares)	25,891,382	23,899,562	23,011,814
Common share equivalents (in shares)	68,566	93,815	76,764
Weighted average common shares (diluted) (in shares)	25,959,948	23,993,377.000	23,088,578
Cash dividends declared (in dollars per share)	$ 1.04	$ 0.96	$ 0.88