Consolidated Obligations (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2013		Mar. 31, 2012	Dec. 31, 2012
Schedule of Short-term and Long-term Debt [Line Items]
Unsecured Debt	$ 45,937,144			$ 44,345,917
Discount Notes	34,075,772			30,840,224
Percent of Fixed Rate Consolidated Obligation Bonds Swapped to Adjustable Rate	17.00%			26.00%
Unamortized Concessions Included in Other Assets	14,579			14,299
Amortization of Concessions Included in Consolidated Obligations Interest Expense During Period	1,733		5,325
Consolidated Obligation Bonds [Member]
Schedule of Short-term and Long-term Debt [Line Items]
Debt, Maturities, Repayments of Principal in Twelve Months	20,341,450			18,656,450
Debt, Maturities, Repayments of Principal in Next Twelve Months, Weighted Average Interest Rate	0.74%			0.82%
Long-term Debt, Maturities, Repayments of Principal in Rolling Year Two	10,291,500
Long-term Debt, Maturities, Repayments of Principal in Year Two				11,371,500
Long-term Debt, Maturities, Repayments of Principal in Year Two, Weighted Average Interest Rate	0.96%			0.83%
Long-term Debt, Maturities, Repayments of Principal in Rolling Year Three	2,069,000
Long-term Debt, Maturities, Repayments of Principal in Year Three				2,566,000
Long-term Debt, Maturities, Repayments of Principal in Year Three, Weighted Average Interest Rate	2.08%			1.96%
Long-term Debt, Maturities, Repayments of Principal in Rolling Year Four	2,722,000
Long-term Debt, Maturities, Repayments of Principal in Year Four				2,550,000
Long-term Debt, Maturities, Repayments of Principal in Year Four, Weighted Average Interest Rate	2.37%			2.62%
Long-term Debt, Maturities, Repayments of Principal in Rolling Year Five	3,107,000
Long-term Debt, Maturities, Repayments of Principal in Year Five				2,654,000
Long-term Debt, Maturities, Repayments of Principal in Year Five, Weighted Average Interest Rate	1.65%			1.81%
Long-term Debt, Maturities, Repayments of Principal in Rolling after Year Five	7,237,000
Long-term Debt, Maturities, Repayments of Principal after Year Five				6,369,000
Long-term Debt, Maturities, Repayments of Principal After Year Five, Weighted Average Interest Rate	2.45%			2.53%
Index amortizing notes	46,100			56,162
Index amortizing notes, Weighted average interest rate	5.07%			5.08%
Debt, Gross	45,814,050			44,223,112
Long-term Debt, Weighted Average Interest Rate	1.28%			1.30%
Debt Instrument, Unamortized Premium	92,169			80,956
Debt Instrument, Unamortized Discount	(20,416)			(18,851)
Debt Valuation Adjustment for Hedging Activities	49,273			58,334
Fair value option valuation adjustment and accrued interest	2,068			2,366
Unsecured Debt	45,937,144			44,345,917
Non Callable [Member] | Consolidated Obligation Bonds [Member]
Schedule of Short-term and Long-term Debt [Line Items]
Debt, Gross	39,052,050			36,724,112
Callable [Member] | Consolidated Obligation Bonds [Member]
Schedule of Short-term and Long-term Debt [Line Items]
Debt, Gross	6,762,000			7,499,000
Earlier of Contractual Maturity or Next Call Date [Member] | Consolidated Obligation Bonds [Member]
Schedule of Short-term and Long-term Debt [Line Items]
Debt, Maturities, Repayments of Principal in Twelve Months	26,258,450			24,370,450
Long-term Debt, Maturities, Repayments of Principal in Rolling Year Two	10,646,500
Long-term Debt, Maturities, Repayments of Principal in Year Two				11,466,500
Long-term Debt, Maturities, Repayments of Principal in Rolling Year Three	1,539,000
Long-term Debt, Maturities, Repayments of Principal in Year Three				1,936,000
Long-term Debt, Maturities, Repayments of Principal in Rolling Year Four	1,812,000
Long-term Debt, Maturities, Repayments of Principal in Year Four				1,860,000
Long-term Debt, Maturities, Repayments of Principal in Rolling Year Five	2,205,000
Long-term Debt, Maturities, Repayments of Principal in Year Five				1,907,000
Long-term Debt, Maturities, Repayments of Principal in Rolling after Year Five	3,307,000
Long-term Debt, Maturities, Repayments of Principal after Year Five				2,627,000
Index amortizing notes	46,100			56,162
Discount Notes [Member]
Schedule of Short-term and Long-term Debt [Line Items]
Discount Notes	34,075,772			30,840,224
Debt Instrument, Face Amount	34,085,246			30,848,612
Short-term Debt, Weighted Average Interest Rate	0.12%	[1]		0.13%	[1]
Fixed-rate [Member] | Consolidated Obligation Bonds [Member]
Schedule of Short-term and Long-term Debt [Line Items]
Debt, Gross	28,224,050			29,393,112
Variable-rate [Member] | Consolidated Obligation Bonds [Member]
Schedule of Short-term and Long-term Debt [Line Items]
Debt, Gross	$ 17,590,000			$ 14,830,000

[1] Represents an implied rate without consideration of concessions.