Investment Securities (Other Disclosures) (Details) (USD $)	0 Months Ended	12 Months Ended
	May 03, 2010	Dec. 31, 2012 securities	Dec. 31, 2011 securities	Dec. 31, 2010
Schedule of Available-for-sale Securities [Line Items]
Held-to-maturity investment securities	$ 83,200,000
Unrealized net gain on held-to-maturity investment securities	3,500,000
Unrealized holding gains arising during the period on reclassifying held-to-maturity securites to available-for-sale securities	2,800,000	0	0	3,478,000
Unrealized holding gains arising during the period on reclassifying held-to-maturity securites to available-for-sale securities, tax effect	700,000	0	0	1,373,000
Investment securities portfolio available as lendable collateral		447,300,000	323,900,000
FHLB stock		6,300,000	10,700,000
FRBR stock		3,100,000	1,200,000
Investment securities that had continuous unrealized losses for more than twelve months		2	7
Deposits [Member]
Schedule of Available-for-sale Securities [Line Items]
Investment securities portfolio pledged as collateral		111,400,000	101,200,000
Federal Reserve Bank of Richmond [Member]
Schedule of Available-for-sale Securities [Line Items]
Investment securities portfolio pledged as collateral		4,000,000	4,100,000
Others [Member]
Schedule of Available-for-sale Securities [Line Items]
Investment securities portfolio pledged as collateral		$ 2,100,000	$ 2,100,000