CONSOLIDATED STATEMENTS OF INCOME - USD ($)	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Interest Income:
Interest and fees on loans	$ 293,131,000	$ 172,091,000	$ 150,868,000
Interest on loans held for sale	1,245,000	279,000	387,000
Interest on deposits with banks	1,304,000	410,000	213,000
Interest and dividends on investment securities:
Taxable	20,516,000	13,881,000	11,500,000
Exempt from federal income taxes	7,855,000	8,111,000	7,583,000
Interest on federal funds sold	31,000	27,000	5,000
Total interest income	324,082,000	194,799,000	170,556,000
Interest Expense:
Interest on deposits	39,139,000	13,256,000	8,161,000
Interest on retail repurchase agreements and federal funds purchased	1,169,000	337,000	290,000
Interest on advances from FHLB	21,408,000	12,426,000	11,610,000
Interest on subordinated debt	1,921,000	12,000	943,000
Total interest expense	63,637,000	26,031,000	21,004,000
Net interest income	260,445,000	168,768,000	149,552,000
Provision for loan losses	9,023,000	2,977,000	5,546,000
Net interest income after provision for loan losses	251,422,000	165,791,000	144,006,000
Investment securities gains	190,000	1,273,000	1,932,000
Insurance agency commissions	6,158,000	6,231,000	5,408,000
Income from bank owned life insurance	4,327,000	2,403,000	2,462,000
Other income	7,126,000	6,331,000	6,759,000
Total non-interest income	61,049,000	51,243,000	51,042,000
Non-interest Expenses:
Salaries and employee benefits	96,998,000	73,132,000	71,354,000
Occupancy expense of premises	18,352,000	13,053,000	12,960,000
Equipment expenses	9,335,000	7,015,000	6,883,000
Marketing	3,924,000	3,119,000	2,851,000
Outside data services	6,603,000	5,486,000	5,377,000
FDIC insurance	5,095,000	3,305,000	2,741,000
Amortization of intangible assets	2,162,000	101,000	130,000
Litigation expense	0	0	0
Merger expenses	11,766,000	4,252,000	0
Other Expense	25,548,000	19,636,000	20,762,000
Total non-interest expenses	179,783,000	129,099,000	123,058,000
Income before income taxes	132,688,000	87,935,000	71,990,000
Income tax expense	31,824,000	34,726,000	23,740,000
Net income	$ 100,864,000	$ 53,209,000	$ 48,250,000
Per share information:
Basic net income per share	$ 2.82	$ 2.2	$ 2
Diluted net income per share	2.82	2.2	2
Dividends declared per common share	$ 1.1	$ 1.04	$ 0.98
Service charges on deposit accounts [Member]
Fees, comminssions and banking services	$ 9,324,000	$ 8,298,000	$ 7,953,000
Mortgage banking activities [Member]
Fees, comminssions and banking services	7,073,000	2,734,000	4,049,000
Wealth managment [Member]
Fees, comminssions and banking services	21,284,000	19,146,000	17,805,000
Bank card fees [member]
Fees, comminssions and banking services	$ 5,567,000	$ 4,827,000	$ 4,674,000