Acquisition of MainStreet - Consideration Paid and Fair Value of Identifiable Assets Acquired and Liabilities Assumed (Details) - USD ($) $ in Thousands		9 Months Ended
	Jan. 01, 2015	Sep. 30, 2015	Sep. 30, 2014	Jun. 30, 2015	Jan. 31, 2015	Dec. 31, 2014	[1]
Consideration Paid:
Common shares issued		$ 20,483	$ 0
Assets acquired:
Investment securities		18,800	0
Restricted stock		587	0
Loans		115,050	0
Core deposit intangible		1,839	0
Other real estate owned		168	0
Bank owned life insurance		1,955	0
Other assets		1,077	0
Liabilities assumed:
Deposits		137,323	0
Other liabilities		3,001	0
Goodwill resulting from merger with MainStreet		44,333	$ 39,043			$ 39,043
Number of additional common stock issued in connection with merger (in shares)	825,586
MainStreet BankShares, Inc.
Consideration Paid:
Common shares issued	$ 20,483
Cash paid to shareholders	5,935
Value of consideration	26,418
Assets acquired:
Cash and cash equivalents	18,173
Investment securities	18,800	18,800
Restricted stock	587
Loans	115,050
Premises and equipment	1,030	1,030
Deferred income taxes	2,773
Core deposit intangible	1,839				$ 1,839
Other real estate owned	168	168
Bank owned life insurance	1,955
Other assets	1,077
Total assets	161,452
Liabilities assumed:
Deposits	137,323
Other liabilities	3,001
Total liabilities	140,324
Net assets acquired	21,128
Goodwill resulting from merger with MainStreet	$ 5,290	$ 5,290		$ 5,167

[1] Derived from audited consolidated financial statements.