CONSOLIDATED STATEMENTS OF NET INCOME - USD ($) $ in Thousands		12 Months Ended
		Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
INTEREST INCOME
Loans, including fees		$ 300,625	$ 269,811	$ 243,315
Investment Securities:
Taxable		14,733	14,342	11,947
Tax-exempt		3,302	3,449	3,615
Dividends		1,824	2,224	1,765
Total Interest Income		320,484	289,826	260,642
INTEREST EXPENSE
Deposits		63,026	40,856	25,330
Borrowings and junior subordinated debt securities		10,667	14,532	9,579
Total Interest Expense		73,693	55,388	34,909
NET INTEREST INCOME		246,791	234,438	225,733
Provision for loan losses		14,873	14,995	13,883
Net Interest Income After Provision for Loan Losses		231,918	219,443	211,850
NONINTEREST INCOME
Net (loss)/gain on sale of securities		(26)	0	3,000
Commercial loan swap income		5,503	1,225	503
Mortgage banking		2,491	2,762	2,915
Insurance		355	505	5,371
Gain on sale of a majority interest of insurance business		0	1,873	0
Other		8,891	6,957	9,428
Total Noninterest Income		52,558	49,181	55,462
NONINTEREST EXPENSE
Salaries and employee benefits		83,986	76,108	80,776
Data processing and information technology		14,468	10,633	8,801
Net occupancy		12,103	11,097	10,994
Merger-related		11,350	0	0
Furniture, equipment and software		8,958	8,083	7,946
Marketing		4,631	4,192	3,659
Professional services and legal		4,244	4,132	4,096
Other taxes		3,364	6,183	4,509
FDIC insurance		758	3,238	4,543
Other		23,254	21,779	22,583
Total Noninterest Expense		167,116	145,445	147,907
Income Before Taxes		117,360	123,179	119,405
Provision for income taxes		19,126	17,845	46,437
Net Income		$ 98,234	$ 105,334	$ 72,968
Earnings per common share—basic (in USD per share)		$ 2.84	$ 3.03	$ 2.10
Earnings per common share—diluted (in USD per share)		2.82	3.01	2.09
Dividends declared per common share (in USD per share)		$ 1.09	$ 0.99	$ 0.82
Debit and credit card
NONINTEREST INCOME
Revenue from contract with customer	[1]	$ 13,405	$ 12,679	$ 12,029
Service charges on deposit accounts
NONINTEREST INCOME
Revenue from contract with customer	[1]	13,316	13,096	12,458
Wealth management
NONINTEREST INCOME
Revenue from contract with customer	[1]	8,623	10,084	9,758
Majority Interest of Insurance Business
NONINTEREST INCOME
Gain on sale of a majority interest of insurance business		$ 0	$ 1,873	$ 0

[1] Refer to Note 1. Summary of Significant Accounting Policies for the types of revenue streams that are included within each category.