Acquisitions (Narrative) (Details) (USD $)	0 Months Ended	3 Months Ended		9 Months Ended				3 Months Ended	9 Months Ended					3 Months Ended	9 Months Ended				9 Months Ended		0 Months Ended	9 Months Ended
	Jan. 10, 2013	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012	Dec. 31, 2012	Dec. 31, 2011	Sep. 30, 2013 Community Bank [Member]	Sep. 30, 2013 Community Bank [Member]	Jan. 10, 2013 Community Bank [Member]	Dec. 31, 2012 Community Bank [Member]	Jan. 10, 2013 Community Bank [Member] Western Virginia [Member] branch	Jan. 10, 2013 Community Bank [Member] Virginia Beach [Member] branch	Sep. 30, 2012 Virginia Savings Bank [Member]	Sep. 30, 2012 Virginia Savings Bank [Member]	Sep. 30, 2013 Virginia Savings Bank [Member]	Dec. 31, 2012 Virginia Savings Bank [Member]	May 31, 2012 Virginia Savings Bank [Member] branch	Sep. 30, 2013 Virginia Savings Bank And Community Financial [Member]	Dec. 31, 2012 Virginia Savings Bank And Community Financial [Member]	Jan. 10, 2013 Warrant [Member] Community Bank [Member]	Sep. 30, 2013 Employee Severance [Member] Community Bank [Member]	Sep. 30, 2012 Employee Severance [Member] Virginia Savings Bank [Member]	Sep. 30, 2013 Professional Fees [Member] Community Bank [Member]	Sep. 30, 2012 Professional Fees [Member] Virginia Savings Bank [Member]	Sep. 30, 2013 Data Processing Costs [Member] Community Bank [Member]	Sep. 30, 2012 Data Processing Costs [Member] Virginia Savings Bank [Member]
Business Acquisition [Line Items]
Percentage of outstanding common and preferred stock										100.00%								100.00%
Number of branches acquired												8	2					5
Assets		$ 3,396,688,000		$ 3,396,688,000		$ 2,917,466,000				$ 460,000,000								$ 132,000,000
Gross loans		2,558,456,000		2,558,456,000		2,146,369,000		288,117,000	288,117,000	410,000,000	0					52,640,000	65,219,000	82,000,000	340,757,000	65,219,000
Deposits		2,807,536,000		2,807,536,000		2,409,316,000				380,000,000								120,000,000
Shareholders equity		378,042,000	328,415,000	378,042,000	328,415,000	333,274,000	311,134,000			53,000,000								11,000,000
Number of shares received by Community shareholders for each share of Community Financial	0.1753
Transaction purchase price		53,641,000		53,641,000						41,246,000								12,395,000
Cash		17,410,000		17,410,000						12,738,000								4,672,000
Number of common stock shares issued										767,000								240,000
Common stock valued		35,506,000		35,506,000						27,783,000								7,723,000
Closing price of common stock at acquisition										$ 36.23								$ 32.18
Number of shares to purchase through warrant																					61,565
Exercise price per share																					$ 30.8
Original warrant expiration period																					10 years
Revised warrant expiration period																					6 years
Goodwill		17,530,000		17,530,000						9,289,000								8,241,000
Core deposit intangible		3,984,000		3,984,000						2,711,000								1,273,000
Premium on time deposits										1,100,000								2,300,000
Premium on time deposits amortization period				5 years
Amortization time period for core deposit intangible assets				10 years
Core deposit annual charge (less than 0.7 million)																			700,000
Merger related costs (less than 0.1 million)		$ (150,000)	$ 157,000	$ 5,455,000	$ 4,335,000			$ 100,000	$ 5,500,000					$ 200,000	$ 4,300,000							$ 2,500,000	$ 900,000	$ 1,400,000	$ 900,000	$ 1,100,000	$ 2,300,000