Borrowed Funds (Details) (USD $)	9 Months Ended	12 Months Ended
	Sep. 30, 2013	Dec. 31, 2012
Borrowed Funds
Repurchase agreements	$ 86,147,000	$ 70,234,000
Remaining maximum borrowing capacity with the FHLB	209,500,000
Borrowed funds
Borrowings from the FHLB	52,246,000	32,600,000
Fixed interest rate note, originating April 1999, due April 2014
Borrowed funds
Borrowings from the FHLB	1,000,000	1,000,000
Interest rate on debt security (as a percent)	5.41%	5.41%
Fixed interest rate note, originating January 2005, due January 2020
Borrowed funds
Borrowings from the FHLB		763,000
Interest rate on debt security (as a percent)		5.14%
Monthly installments		11,000
Fixed interest rate note, originating April 2002, due May 2017
Borrowed funds
Borrowings from the FHLB	602,000	615,000
Interest rate on debt security (as a percent)	5.90%	5.90%
Fixed interest rate note, originating July 2006, due July 2016
Borrowed funds
Borrowings from the FHLB	1,225,000	1,258,000
Interest rate on debt security (as a percent)	4.50%	4.50%
Monthly installments	8,000	8,000
Fixed interest rate note, originating October 2006, due October 2021
Borrowed funds
Borrowings from the FHLB	1,030,000	1,047,000
Interest rate on debt security (as a percent)	5.20%	5.20%
Monthly installments	6,000	6,000
Fixed interest rate note, originating February 2007, due February 2022
Borrowed funds
Borrowings from the FHLB	865,000	879,000
Interest rate on debt security (as a percent)	5.22%	5.22%
Monthly installments	5,000	5,000
Fixed interest rate note, originating April 2007, due April 2022
Borrowed funds
Borrowings from the FHLB	979,000	995,000
Interest rate on debt security (as a percent)	5.18%	5.18%
Monthly installments	6,000	6,000
Floating interest rate note, originating March 2003
Borrowed funds
Borrowings from the FHLB	45,588,000	23,065,000
Interest rate on debt security at period end (as a percent)	0.25%	0.25%
Fixed interest rate note, originating December 2007, due December 2017
Borrowed funds
Borrowings from the FHLB	957,000	978,000
Interest rate on debt security (as a percent)	5.25%	5.25%
Monthly installments	7,000	7,000
Fixed interest rate note originating March 2008, due March 2013
Borrowed funds
Borrowings from the FHLB		$ 2,000,000
Interest rate on debt security (as a percent)		2.37%