Company-Obligated Mandatorily Redeemable Capital Securities (Details) (USD $)	12 Months Ended		12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2012 Floating Rate Junior Subordinated Deferrable Interest Debentures [Member]	Dec. 31, 2012 Floating Rate Capital Securities [Member]	Dec. 31, 2006 Floating Rate Capital Securities [Member]	Sep. 21, 2006 Floating Rate Capital Securities [Member]
Class of Stock [Line Items]
Face amount of capital securities						$ 4,000,000
Capital securities, basis spread on variable rate (in hundredths)						1.70%
Capital securities, description of variable rate basis					three month LIBOR
Capital securities	4,124,000	4,124,000
Callable period of capital securities				5 years
Debt Instrument [Line Items]
Principal amount of debt			$ 4,000,000
Maturity date	Dec. 31, 2036
Callable period of debt			P5Y