Goodwill and Other Intangible Assets (Details) - USD ($) $ in Thousands			1 Months Ended		3 Months Ended		9 Months Ended
		Jan. 01, 2015	Jan. 31, 2015	Jul. 31, 2011	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Acquired Finite-Lived Intangible Assets [Line Items]
Core deposit intangible					$ 1,839	$ 0	$ 1,839	$ 0
Changes in the carrying amount of goodwill [Roll Forward]
Goodwill	[1]	$ 39,043	$ 39,043				39,043
Goodwill, Additions							5,290
Goodwill, Amortization							0
Goodwill, Impairment							0
Goodwill					44,333	39,043	44,333	39,043
Finite-lived Intangible Assets [Roll Forward]
Intangibles, Balance as of December 31, 2104		2,045	2,045				2,045
Intangibles, Additions							1,839
Intangibles, Amortization					(300)	$ (227)	(901)	$ (888)
Intangibles, Impairment							0
Intangibles, Balance as of June 30, 2015					2,983		2,983
MidCarolina [Member]
Acquired Finite-Lived Intangible Assets [Line Items]
Core deposit intangible				$ 3,112
Amortization period of intangible				120 months
MainStreet BankShares, Inc.
Acquired Finite-Lived Intangible Assets [Line Items]
Core deposit intangible		$ 1,839	$ 1,839
Amortization period of intangible		10 years	120 months
Changes in the carrying amount of goodwill [Roll Forward]
Goodwill					5,167
Goodwill		$ 5,290			$ 5,290		$ 5,290

[1] Derived from audited consolidated financial statements.