Long-term Borrowings (Details) - USD ($)	3 Months Ended
	Mar. 31, 2017	Dec. 31, 2016		Jan. 01, 2015
Debt Disclosure [Abstract]
Percentage of entity's assets equal to line of credit facility	30.00%
Collateral pledged under blanket floating lien agreement	$ 434,467,000
Long term advances with federal home loan bank [Abstract]
Advance Amount	9,985,000	$ 9,980,000	[1]
Advances due, net of fair value discount	15,000
Public deposit accounts	$ 223,193,000
MainStreet BankShares, Inc.
Long term advances with federal home loan bank [Abstract]
Long-term borrowings acquired				$ 0
Amount of loan taken to fund merger				$ 0
November 2017
Long term advances with federal home loan bank [Abstract]
Due by	Nov. 30, 2017
Advance Amount	$ 9,985,000	$ 9,980,000
November 2017 | Weighted Average
Long term advances with federal home loan bank [Abstract]
Weighted Average Rate	2.98%	2.98%
Federal Home Loan Bank Advances
Long term advances with federal home loan bank [Abstract]
Outstanding letters of credit	$ 160,700,000
US government and agency securities
Long term advances with federal home loan bank [Abstract]
Outstanding letters of credit	$ 113,215,000

[1] Derived from audited consolidated financial statements.