Business Combinations - Consideration, Assets Acquired and Liabilities Assumed (Details) - USD ($)						3 Months Ended	4 Months Ended
		Mar. 31, 2020	Dec. 31, 2019	Nov. 30, 2019		Mar. 31, 2020	Mar. 31, 2020
Fair Value of Assets Acquired
Adjustments, Loans		$ (10,900,000)	$ (12,300,000)
Goodwill		374,270,000	371,621,000			$ 374,270,000	$ 374,270,000
Fair Value of Liabilities Assumed
Goodwill		374,270,000	$ 371,621,000			374,270,000	374,270,000
As Recorded by DNB
Fair Value of Assets Acquired
Cash and cash equivalents				$ 64,119,000
Securities and other investments				108,715,000
Loans				917,127,000
Allowance for credit losses				(6,487,000)
Goodwill				15,525,000
Premises and equipment				6,782,000
Accrued interest receivable				4,138,000
Deferred income taxes				2,017,000
Core deposits and other intangible assets				269,000
Other assets				24,883,000
Total Assets Acquired				1,137,088,000
Fair Value of Liabilities Assumed
Deposits				966,263,000
Borrowings				37,617,000
Accrued interest payable and other liabilities				11,157,000
Total Liabilities Assumed				1,015,037,000
Total Net Assets Acquired				122,051,000
Identifiable Intangible Assets				269,000
Goodwill				15,525,000
DNB
Fair Value of Assets Acquired
Cash and cash equivalents		64,119,000		64,119,000		64,119,000	64,119,000
Adjustments, Cash and cash equivalents				0	[1]		0
Securities and other investments		108,898,000		108,898,000		108,898,000	108,898,000
Adjustments, Securities and other investments				183,000	[1]		0
Loans		906,488,000		908,984,000		906,488,000	906,488,000
Adjustments, Loans				(8,143,000)	[1]	2,500,000	(2,496,000)
Allowance for credit losses		0		0		0	0
Adjustments, Allowance for credit losses				6,487,000	[1]		0
Goodwill		85,983,000		84,175,000		85,983,000	85,983,000
Adjustments, Goodwill				(15,525,000)	[1]		1,808,000
Premises and equipment		14,872,000		14,872,000		14,872,000	14,872,000
Adjustments, Premises and equipment				8,090,000	[1]		0
Accrued interest receivable		4,138,000		4,138,000		4,138,000	4,138,000
Adjustments, Accrued interest receivable				0	[1]		0
Deferred income taxes		(970,000)		(1,281,000)		(970,000)	(970,000)
Adjustments, Deferred income taxes				(3,298,000)	[1]		311,000
Adjustments, Core deposits and other intangible assets	[1]			(269,000)
Other assets		20,645,000		20,605,000		20,645,000	20,645,000
Adjustments, Other assets				(4,278,000)	[1]		40,000
Total Assets Acquired		1,118,190,000		1,120,335,000		1,118,190,000	1,118,190,000
Adjustments, Total Assets Acquired				(16,753,000)	[1]		(2,145,000)
Fair Value of Liabilities Assumed
Deposits		967,253,000		967,265,000		967,253,000	967,253,000
Adjustments, Deposits				1,002,000	[1]		(12,000)
Borrowings		37,084,000		37,341,000		37,084,000	37,084,000
Adjustments, Borrowings				(276,000)	[1]		(257,000)
Accrued interest payable and other liabilities		7,905,000		7,973,000		7,905,000	7,905,000
Adjustments, Accrued interest payable and other liabilities				(3,184,000)	[1]		(68,000)
Total Liabilities Assumed		1,012,242,000		1,012,579,000		1,012,242,000	1,012,242,000
Adjustments, Total Liabilities Assumed				(2,458,000)	[1]		(337,000)
Total Net Assets Acquired		105,948,000		107,756,000		105,948,000	105,948,000
Adjustments, Total Net Assets Acquired				(14,295,000)	[1]		(1,808,000)
Total Fair Value of Net Assets Acquired and Identified		115,008,000		116,816,000		115,008,000	115,008,000
Adjustments, Total Fair Value of Net Assets Acquired and Identified							(1,808,000)
Cash				360,000
Common stock				200,631,000
Fair Value of Total Consideration				200,991,000
Goodwill		85,983,000		84,175,000		85,983,000	85,983,000
Core deposits | DNB
Fair Value of Assets Acquired
Core deposits and other intangible assets		7,288,000		7,288,000		7,288,000	7,288,000
Adjustments, Core deposits and other intangible assets							0
Fair Value of Liabilities Assumed
Identifiable Intangible Assets		7,288,000		7,288,000		7,288,000	7,288,000
Wealth management | DNB
Fair Value of Assets Acquired
Core deposits and other intangible assets		1,772,000		1,772,000		1,772,000	1,772,000
Adjustments, Core deposits and other intangible assets							0
Fair Value of Liabilities Assumed
Identifiable Intangible Assets		$ 1,772,000		$ 1,772,000		$ 1,772,000	$ 1,772,000

[1] Management is continuing to evaluate the purchase accounting fair value adjustments related to loans, including loan classification, deferred and current income taxes until the final valuations are complete and final tax returns are filed. Any changes in preliminary estimates will be adjusted in goodwill in subsequent periods, but not extending beyond one year from the date of acquisition.