Consolidated Statements of Income - USD ($)	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Interest income
Interest and fees on loans	$ 294,293,000	$ 253,131,000	$ 224,244,000
Interest Income, Securities, Operating, Taxable	26,513,000	22,465,000	20,851,000
Nontaxable interest and dividends on securities	60,000	88,000	117,000
Interest on loans held for sale	159,000	92,000	235,000
Interest on federal funds sold and short-term investments	2,676,000	1,418,000	1,190,000
Total interest and dividend income	323,701,000	277,194,000	246,637,000
Interest expense
Interest on deposits	19,995,000	12,702,000	11,140,000
Interest on borrowings	5,541,000	5,632,000	7,653,000
Total interest expense	25,536,000	18,334,000	18,793,000
Net interest income	298,165,000	258,860,000	227,844,000
Provision (benefit)	4,775,000	2,950,000	6,075,000
Net interest income after provision for loan losses	293,390,000	255,910,000	221,769,000
Noninterest income
Deposit account fees	18,327,000	17,822,000	18,652,000
Interchange and ATM fees	18,916,000	17,291,000	16,210,000
Investment Banking, Advisory, Brokerage, and Underwriting Fees and Commissions	26,155,000	23,802,000	21,809,000
Fees and Commission Mortgage Banking	4,071,000	4,960,000	6,607,000
Increase in cash surrender value of life insurance policies	4,060,000	4,127,000	4,089,000
Gain Realized on Life Insurance Policies	1,463,000	0
Loan level derivative income	2,373,000	3,836,000	6,155,000
Other noninterest income	13,140,000	11,156,000	8,906,000
Total noninterest income	88,505,000	82,994,000	82,428,000
Noninterest expenses
Salaries and employee benefits	124,328,000	116,600,000	108,636,000
Occupancy and equipment expenses	27,098,000	24,693,000	22,867,000
Data processing & facilities management	5,125,000	4,988,000	4,975,000
FDIC assessment	2,774,000	3,068,000	3,380,000
Advertising expense	4,942,000	4,989,000	5,202,000
Consulting expense	3,891,000	4,038,000	3,486,000
Debit Card Expense	3,429,000	3,430,000	2,993,000
Gains (Losses) on Extinguishment of Debt	0	0	437,000
Merger and acquisition expense	11,168,000	3,393,000	5,455,000
Software Maintenance	4,202,000	3,636,000	3,061,000
Other noninterest expenses	39,012,000	35,524,000	31,630,000
Total noninterest expenses	225,969,000	204,359,000	192,122,000
Income before income taxes	155,926,000	134,545,000	112,075,000
Provision for income taxes	34,304,000	47,341,000	35,427,000
Net Income	$ 121,622,000	$ 87,204,000	$ 76,648,000
Basic earnings per share (in dollars per share)	$ 4.41	$ 3.19	$ 2.90
Diluted earnings per share (in dollars per share)	$ 4.40	$ 3.19	$ 2.90
Weighted average common shares (basic) (in shares)	27,592,380	27,294,028	26,404,071
Common share equivalents (in shares)	61,428	78,076	51,847
Weighted average common shares (diluted) (in shares)	27,653,808	27,372,104	26,455,918
Retained Earnings
Noninterest expenses
Net Income	$ 121,622,000	$ 87,204,000	$ 76,648,000
Cash dividends declared (in dollars per share)	$ 1.52	$ 1.28	$ 1.16