Commitment, Changes in the Allowance for Unfunded Commitments (Details) - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
	Mar. 31, 2021	Dec. 31, 2020	Jan. 01, 2020
Off-Balance Sheet, Credit Loss, Liability [Roll Forward]
Balance at beginning of period	$ 47,776	$ 21,907
Off-Balance Sheet, Credit Loss, Liability	47,776	47,776
Provision for credit losses	3,000	7,000
Balance at end of period	$ 50,776	47,776
Cumulative Effect, Period Of Adoption, Adjusted Balance
Off-Balance Sheet, Credit Loss, Liability [Roll Forward]
Off-Balance Sheet, Credit Loss, Liability			$ 40,597
First Staunton Bancshares [Member]
Off-Balance Sheet, Credit Loss, Liability [Roll Forward]
Provision for credit losses		$ 179
Accounting Standards Update 2016-13 | Cumulative Effect, Period Of Adoption, Adjustment
Off-Balance Sheet, Credit Loss, Liability [Roll Forward]
Off-Balance Sheet, Credit Loss, Liability			$ 18,690