Advances (Advances by Year of Contractual Maturity or Next Put/Convert Date for Putable/Convertible Advances) (Details) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2013	Dec. 31, 2012
Advances [Abstract]
Overdrawn Demand Deposit Accounts	$ 459	$ 0
Federal Home Loan Bank, Advances, Earlier of Contractual Maturity or Next Put Date, Due within One Year of Balance Sheet Date	8,414,011
Federal Home Loan Bank, Advances, Earlier of Contractual Maturity or Next Put Date, Due within One Year of Balance Sheet Date		14,792,295
Federal Home Loan Bank, Advances, Earlier of Contractual Maturity or Next Put Date, Due From One To Two Years of Balance Sheet Date	8,309,828
Federal Home Loan Bank, Advances, Earlier of Contractual Maturity or Next Put Date, Due From One To Two Years of Balance Sheet Date		4,672,041
Federal Home Loan Bank, Advances, Earlier of Contractual Maturity or Next Put Date, Due From Two To Three Years of Balance Sheet Date	7,752,061
Federal Home Loan Bank, Advances, Earlier of Contractual Maturity or Next Put Date, Due From Two To Three Years of Balance Sheet Date		6,193,507
Federal Home Loan Bank, Advances, Earlier of Contractual Maturity or Next Put Date, Due From Three To Four Years of Balance Sheet Date	7,889,057
Federal Home Loan Bank, Advances, Earlier of Contractual Maturity or Next Put Date, Due From Three To Four Years of Balance Sheet Date		6,019,525
Federal Home Loan Bank, Advances, Earlier of Contractual Maturity or Next Put Date, Due From Four To Five Years of Balance Sheet Date	8,002,569
Federal Home Loan Bank, Advances, Earlier of Contractual Maturity or Next Put Date, Due From Four To Five Years of Balance Sheet Date		8,125,303
Federal Home Loan Bank, Advances, Earlier of Contractual Maturity or Next Put Date, Due After Five Years of Balance Sheet Date	17,631,067
Federal Home Loan Bank, Advances, Earlier of Contractual Maturity or Next Put Date, Due After Five Years of Balance Sheet Date		13,818,107
Federal Home Loan Bank Advances At Par Value	$ 57,999,052	$ 53,620,778