Estimated Fair Values (Carrying Value and Fair Value of Financial Instruments) (Details) (USD $) In Thousands, unless otherwise specified	Sep. 30, 2013		Dec. 31, 2012
Assets
Trading securities	$ 708,603		$ 7,541
Available-for-sale securities	5,516,079		5,772,153
Held-to-maturity Securities	5,153,825	[1]	5,199,875	[1]
Held-to-maturity Securities, Fair Value	5,209,238		5,283,965
Derivative assets	14,441		13,947
Consolidated Obligations
Discount notes	6,513,829		6,984,378
Bonds	22,041,996		25,697,936
Mandatorily redeemable capital stock	30,086		4,504
Derivative liabilities	9,996		11,268
Carrying Value [Member]
Assets
Cash and due from banks	883,037		920,780
Interest-bearing deposits	368		254
Securities purchased under agreements to resell	500,000		3,000,000
Federal funds sold	1,706,000		2,219,000
Trading securities	708,603	[2]	7,541	[3]
Available-for-sale securities	5,516,079	[2]	5,772,153	[3]
Held-to-maturity Securities	5,153,825		5,199,875
Advances	16,634,235		18,394,797
Mortgage loans held for portfolio, net	96,263		121,478
Accrued interest receivable	78,440		72,531
Derivative assets	14,441	[2]	13,947	[3]
Liabilities
Deposits	875,896		1,177,964
Consolidated Obligations
Discount notes	6,513,829		6,984,378
Bonds	22,041,996		25,697,936
Mandatorily redeemable capital stock	30,086		4,504
Accrued interest payable	48,859		53,940
Derivative liabilities	9,996	[2]	11,268	[3]
Estimated Fair Value [Member]
Assets
Cash and due from banks	883,037		920,780
Interest-bearing deposits	368		254
Securities purchased under agreements to resell	500,000		3,000,000
Federal funds sold	1,706,000		2,219,000
Trading securities	708,603	[2]	7,541	[3]
Available-for-sale securities	5,516,079	[2]	5,772,153	[3]
Held-to-maturity Securities, Fair Value	5,209,238		5,283,965
Advances	16,699,795		18,552,112
Mortgage loans held for portfolio, net	105,065		134,562
Accrued interest receivable	78,440		72,531
Derivative assets	14,441	[2]	13,947	[3]
Liabilities
Deposits	875,896		1,177,961
Consolidated Obligations
Discount notes, Fair Value	6,514,160		6,985,001
Bonds, Fair Value	22,013,973		25,836,987
Mandatorily redeemable capital stock	30,086		4,504
Accrued interest payable	48,859		53,940
Derivative liabilities	9,996	[2]	11,268	[3]
Estimated Fair Value [Member] | Level 1 [Member]
Assets
Cash and due from banks	883,037		920,780
Interest-bearing deposits	0		0
Securities purchased under agreements to resell	0		0
Federal funds sold	0		0
Trading securities	9,016	[2]	7,541	[3]
Available-for-sale securities	0	[2]	0	[3]
Held-to-maturity Securities, Fair Value	0		0
Advances	0		0
Mortgage loans held for portfolio, net	0		0
Accrued interest receivable	0		0
Derivative assets	0	[2]	0	[3]
Liabilities
Deposits	0		0
Consolidated Obligations
Discount notes, Fair Value	0		0
Bonds, Fair Value	0		0
Mandatorily redeemable capital stock	30,086		4,504
Accrued interest payable	0		0
Derivative liabilities	0	[2]	0	[3]
Estimated Fair Value [Member] | Level 2 [Member]
Assets
Cash and due from banks	0		0
Interest-bearing deposits	368		254
Securities purchased under agreements to resell	500,000		3,000,000
Federal funds sold	1,706,000		2,219,000
Trading securities	699,587	[2]	0	[3]
Available-for-sale securities	5,516,079	[2]	5,772,153	[3]
Held-to-maturity Securities, Fair Value	5,022,292	[4]	5,076,751	[4]
Advances	16,699,795		18,552,112
Mortgage loans held for portfolio, net	105,065		134,562
Accrued interest receivable	78,440		72,531
Derivative assets	82,258	[2]	118,714	[3]
Liabilities
Deposits	875,896		1,177,961
Consolidated Obligations
Discount notes, Fair Value	6,514,160		6,985,001
Bonds, Fair Value	22,013,973		25,836,987
Mandatorily redeemable capital stock	0		0
Accrued interest payable	48,859		53,940
Derivative liabilities	969,900	[2]	1,344,588	[3]
Estimated Fair Value [Member] | Level 3 [Member]
Assets
Cash and due from banks	0		0
Interest-bearing deposits	0		0
Securities purchased under agreements to resell	0		0
Federal funds sold	0		0
Trading securities	0	[2]	0	[3]
Available-for-sale securities	0	[2]	0	[3]
Held-to-maturity Securities, Fair Value	186,946	[5]	207,214	[5]
Advances	0		0
Mortgage loans held for portfolio, net	0		0
Accrued interest receivable	0		0
Derivative assets	0	[2]	0	[3]
Liabilities
Deposits	0		0
Consolidated Obligations
Discount notes, Fair Value	0		0
Bonds, Fair Value	0		0
Mandatorily redeemable capital stock	0		0
Accrued interest payable	0		0
Derivative liabilities	0	[2]	0	[3]
Estimated Fair Value [Member] | Netting Adjustment [Member]
Assets
Cash and due from banks	0	[6]	0	[7]
Interest-bearing deposits	0	[6]	0	[7]
Securities purchased under agreements to resell	0	[6]	0	[7]
Federal funds sold	0	[6]	0	[7]
Trading securities	0	[2],[6]	0	[3],[7]
Available-for-sale securities	0	[2],[6]	0	[3],[7]
Held-to-maturity Securities, Fair Value	0	[6]	0	[7]
Advances	0	[6]	0	[7]
Mortgage loans held for portfolio, net	0	[6]	0	[7]
Accrued interest receivable	0	[6]	0	[7]
Derivative assets	(67,817)	[2],[6]	(104,767)	[3],[7]
Liabilities
Deposits	0	[6]	0	[7]
Consolidated Obligations
Discount notes, Fair Value	0	[6]	0	[7]
Bonds, Fair Value	0	[6]	0	[7]
Mandatorily redeemable capital stock	0	[6]	0	[7]
Accrued interest payable	0	[6]	0	[7]
Derivative liabilities	$ (959,904)	[2],[6]	$ (1,333,320)	[3],[7]

[1] (a)Fair values: $5,209,238 and $5,283,965 at September 30, 2013 and December 31, 2012, respectively.

[2] Financial instruments measured at fair value on a recurring basis as of September 30, 2013.

[3] Financial instruments measured at fair value on a recurring basis as of December 31, 2012.

[4] Consists of the Bank's holdings of U.S. government-guaranteed debentures, U.S. government-guaranteed MBS and GSE MBS.

[5] Consists of the Bank's holdings of non-agency RMBS.

[6] Amounts represent the impact of legally enforceable master netting agreements or other legally enforceable arrangements between the Bank and its derivative counterparties that allow the Bank to offset positive and negative positions as well as the cash collateral held or placed with those same counterparties.

[7] Amounts represent the impact of legally enforceable master netting agreements between the Bank and its bilateral derivative counterparties that allow the Bank to offset positive and negative positions as well as the cash collateral held or placed with those same counterparties.