Goodwill and Other Intangible Assets Goodwill and Other Intangible Assets (Details) - USD ($) $ in Thousands		1 Months Ended		3 Months Ended		9 Months Ended
		Jan. 31, 2015	Jul. 31, 2011	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Goodwill
Beginning Balance	[1]					$ 43,872
Additions						0
Amortization						0
Impairment						0
Ending Balance				$ 43,872	$ 43,872	43,872	$ 43,872
Intangibles
Beginning Balance						1,719
Additions						0
Amortization				(80)	$ (213)	(448)	$ (789)
Impairment						0
Ending Balance				$ 1,271		$ 1,271
MidCarolina
Acquired Finite-Lived Intangible Assets [Line Items]
Core deposit intangible			$ 6,556
Amortization period of intangible			108 months
MainStreet BankShares, Inc.
Acquired Finite-Lived Intangible Assets [Line Items]
Core deposit intangible		$ 1,839
Amortization period of intangible		120 months

[1] Derived from audited consolidated financial statements.