Trust Preferred Securities - Additional Information (Details) (USD $)	1 Months Ended	6 Months Ended
	May 31, 2007	Jun. 30, 2013	Dec. 31, 2012
Trust Preferred Securities [Line Items]
Accrued interest payable		$ 825,000	$ 882,000
Maturity date of subordinate notes		Jun. 15, 2037
Trust I [Member]
Trust Preferred Securities [Line Items]
Preferred securities sold to outside investors	10,000,000.0
Floating interest rate period	three-month LIBOR
LIBOR basis points	1.48%
Effective interest rate		1.75%
Accrued interest payable		5,000	19,000
Trust II [Member]
Trust Preferred Securities [Line Items]
Preferred securities sold to outside investors	10,000,000.0
Floating interest rate period	three-month LIBOR
LIBOR basis points	1.48%
Fixed interest rate of Trust II	6.64%
Effective interest rate		6.64%
Accrued interest payable		$ 19,000	$ 21,000