Fair Value Disclosures Fair Value Summary (Details) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2013		Dec. 31, 2012		Mar. 31, 2012	Dec. 31, 2011
Assets
Derivative assets	$ 4,834		$ 5,877
Liabilities
Consolidated Obligations, Bonds	2,002,068		3,402,366		4,202,540	4,900,296
Mandatorily redeemable capital stock	133,955		210,828
Carrying Value
Assets
Cash and Due from Banks	343,785		16,423
Interest-bearing deposits	125		151
Securities purchased under resale agreements	2,950,000		3,800,000
Federal funds sold	3,600,000		3,350,000
Trading securities	1,841		1,922
Available-for-sale securities	500,044
Held-to-maturity securities	13,720,233		12,798,448
Advances	58,282,314		53,943,961
Mortgage loans held for portfolio, net	7,212,481		7,530,112
Accrued interest receivable	83,780		83,904
Derivative assets	4,834		5,877
Liabilities
Deposits	1,101,570		1,176,605
Mandatorily redeemable capital stock	133,955		210,828
Accrued Interest Payable, Fair Value Disclosure	120,946		106,885
Derivative liabilities	108,930		114,888
Fair Value
Assets
Cash and Due from Banks	343,785		16,423
Interest-bearing deposits	125		151
Securities purchased under resale agreements	2,950,000		3,800,000
Federal funds sold	3,600,000		3,350,000
Trading securities	1,841		1,922
Available-for-sale securities	500,044
Held-to-maturity securities	14,058,463		13,177,117
Advances	58,315,195		54,070,350
Mortgage loans held for portfolio, net	7,499,270		7,860,090
Accrued interest receivable	83,780		83,904
Derivative assets	4,834		5,877
Liabilities
Deposits	1,101,415		1,176,474
Mandatorily redeemable capital stock	133,955		210,828
Accrued Interest Payable, Fair Value Disclosure	120,946		106,885
Derivative liabilities	108,930		114,888
Consolidated Obligation Bonds [Member] | Carrying Value
Liabilities
Consolidated Obligations, Bonds	45,937,144	[1]	44,345,917	[2]
Consolidated Obligation Bonds [Member] | Fair Value
Liabilities
Consolidated Obligations, Bonds	46,578,516	[1]	45,069,294	[2]
Consolidated Obligation Bonds [Member] | Portion at Fair Value, Fair Value Disclosure [Member]
Liabilities
Consolidated Obligations, Bonds	2,002,068		3,402,366
Fair Value, Inputs, Level 1 [Member]
Assets
Cash and Due from Banks	343,785		16,423
Interest-bearing deposits	0		0
Securities purchased under resale agreements	0		0
Federal funds sold	0		0
Trading securities	0		0
Available-for-sale securities	0
Held-to-maturity securities	0		0
Advances	0		0
Mortgage loans held for portfolio, net	0		0
Accrued interest receivable	0		0
Derivative assets	0		0
Liabilities
Deposits	0		0
Mandatorily redeemable capital stock	133,955		210,828
Accrued Interest Payable, Fair Value Disclosure	0		0
Derivative liabilities	0		0
Fair Value, Inputs, Level 1 [Member] | Consolidated Obligation Bonds [Member]
Liabilities
Consolidated Obligations, Bonds	0	[1]	0	[2]
Fair Value, Inputs, Level 2 [Member]
Assets
Cash and Due from Banks	0		0
Interest-bearing deposits	125		151
Securities purchased under resale agreements	2,950,000		3,800,000
Federal funds sold	3,600,000		3,350,000
Trading securities	1,841		1,922
Available-for-sale securities	500,044
Held-to-maturity securities	14,058,463		13,177,117
Advances	58,315,195		54,070,350
Mortgage loans held for portfolio, net	7,436,133		7,790,290
Accrued interest receivable	83,780		83,904
Derivative assets	59,236		69,677
Liabilities
Deposits	1,101,415		1,176,474
Mandatorily redeemable capital stock	0		0
Accrued Interest Payable, Fair Value Disclosure	120,946		106,885
Derivative liabilities	342,996		389,473
Fair Value, Inputs, Level 2 [Member] | Consolidated Obligation Bonds [Member]
Liabilities
Consolidated Obligations, Bonds	46,578,516	[1]	45,069,294	[2]
Fair Value, Inputs, Level 3 [Member]
Assets
Cash and Due from Banks	0		0
Interest-bearing deposits	0		0
Securities purchased under resale agreements	0		0
Federal funds sold	0		0
Trading securities	0		0
Available-for-sale securities	0
Held-to-maturity securities	0		0
Advances	0		0
Mortgage loans held for portfolio, net	63,137		69,800
Accrued interest receivable	0		0
Derivative assets	0		0
Liabilities
Deposits	0		0
Mandatorily redeemable capital stock	0		0
Accrued Interest Payable, Fair Value Disclosure	0		0
Derivative liabilities	0		0
Fair Value, Inputs, Level 3 [Member] | Consolidated Obligation Bonds [Member]
Liabilities
Consolidated Obligations, Bonds	0	[1]	0	[2]
Netting and Collateral [Member]
Assets
Cash and Due from Banks	0	[3]	0	[3]
Interest-bearing deposits	0	[3]	0	[3]
Securities purchased under resale agreements	0	[3]	0	[3]
Federal funds sold	0	[3]	0	[3]
Trading securities	0	[3]	0	[3]
Available-for-sale securities	0	[3]
Held-to-maturity securities	0	[3]	0	[3]
Advances	0	[3]	0	[3]
Mortgage loans held for portfolio, net	0	[3]	0	[3]
Accrued interest receivable	0	[3]	0	[3]
Derivative assets	(54,402)	[3]	(63,800)	[3]
Liabilities
Deposits	0	[3]	0	[3]
Mandatorily redeemable capital stock	0	[3]	0	[3]
Accrued Interest Payable, Fair Value Disclosure	0	[3]	0	[3]
Derivative liabilities	(234,066)	[3]	(274,585)	[3]
Netting and Collateral [Member] | Consolidated Obligation Bonds [Member]
Liabilities
Consolidated Obligations, Bonds	0	[1],[3]	0	[2],[3]
Discount Notes [Member] | Carrying Value
Liabilities
Consolidated Obligations, Discount Notes	34,075,772		30,840,224
Discount Notes [Member] | Fair Value
Liabilities
Consolidated Obligations, Discount Notes	34,077,620		30,843,064
Discount Notes [Member] | Fair Value, Inputs, Level 1 [Member]
Liabilities
Consolidated Obligations, Discount Notes	0		0
Discount Notes [Member] | Fair Value, Inputs, Level 2 [Member]
Liabilities
Consolidated Obligations, Discount Notes	34,077,620		30,843,064
Discount Notes [Member] | Fair Value, Inputs, Level 3 [Member]
Liabilities
Consolidated Obligations, Discount Notes	0		0
Discount Notes [Member] | Netting and Collateral [Member]
Liabilities
Consolidated Obligations, Discount Notes	0	[3]	0	[3]
Commitments for Standby Bond Purchases [Member] | Carrying Value
Other [Abstract]
Standby bond purchase agreements	0		0
Commitments for Standby Bond Purchases [Member] | Fair Value
Other [Abstract]
Standby bond purchase agreements	3,251		1,198
Commitments for Standby Bond Purchases [Member] | Fair Value, Inputs, Level 1 [Member]
Other [Abstract]
Standby bond purchase agreements	0		0
Commitments for Standby Bond Purchases [Member] | Fair Value, Inputs, Level 2 [Member]
Other [Abstract]
Standby bond purchase agreements	3,251		1,198
Commitments for Standby Bond Purchases [Member] | Fair Value, Inputs, Level 3 [Member]
Other [Abstract]
Standby bond purchase agreements	0		0
Commitments for Standby Bond Purchases [Member] | Netting and Collateral [Member]
Other [Abstract]
Standby bond purchase agreements	$ 0	[3]	$ 0	[3]

[1] Includes (in thousands) $2,002,068 of Consolidated Bonds recorded under the fair value option at March 31, 2013.

[2] Includes (in thousands) $3,402,366 of Consolidated Bonds recorded under the fair value option at December 31, 2012.

[3] Amounts represent the effects of legally enforceable master netting agreements that allow the FHLBank to settle positive and negative positions and of cash collateral held or placed with the same counterparties.