Affordable Housing Program ("AHP") (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Affordable Housing Program [Roll Forward]
AHP, Beginning of period			$ 29,620	$ 32,313
AHP assessment	3,282	1,973	7,750	7,172
Grants funded, net of recaptured amounts			(6,454)	(8,710)
AHP, End of period	$ 30,916	$ 30,775	$ 30,916	$ 30,775