Goodwill and Other Intangible Assets (Details) - USD ($) $ in Thousands			1 Months Ended		3 Months Ended		6 Months Ended
		Jan. 01, 2015	Jan. 31, 2015	Jul. 31, 2011	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Acquired Finite-Lived Intangible Assets [Line Items]
Core deposit intangible		$ 1,839			$ 1,839	$ 0	$ 1,839	$ 0
Amortization period of intangible		10 years
Changes in the carrying amount of goodwill [Roll Forward]
Goodwill, Balance as of December 31, 2014	[1]	$ 39,043	$ 39,043				39,043
Goodwill, Additions							5,167
Goodwill, Amortization							0
Goodwill, Impairment							0
Goodwill, Balance as of June 30, 2015		5,167			44,210	39,043	44,210	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)	$ (330)	(601)	$ (661)
Intangibles, Impairment							0
Intangibles, Balance as of June 30, 2015					$ 3,283		$ 3,283
MidCarolina [Member]
Acquired Finite-Lived Intangible Assets [Line Items]
Core deposit intangible				$ 3,112
Amortization period of intangible				120 months
MainStreet BankShares, Inc. [Member]
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.