Fair Value (Carrying Value and Fair Value of Financial Instruments) (Details) - USD ($) $ in Millions	Mar. 31, 2020	Dec. 31, 2019	Mar. 31, 2019	Dec. 31, 2018
Assets
Cash and due from banks	$ 611	$ 1,029
Trading securities	1,728	888
Available-for-sale securities	16,166	16,651
Held-to-maturity securities	2,254	2,370
Held-to-Maturity Securities, Fair Value	2,346	2,439
Accrued interest receivable	179	195
Derivative assets, net	233	102
Derivative Asset, Fair Value, Gross Liability and Obligation to Return Cash, Offset	162	63
Liabilities
Derivative Liability, Fair Value, Gross Asset and Right to Reclaim Cash, Offset	447	201
Mandatorily redeemable capital stock	(96)	(206)	$ (237)	$ (255)
Accrued interest payable	(258)	(252)
Derivative liabilities, net	(9)	(1)
Reported Value Measurement [Member]
Assets
Cash and due from banks	611	1,029
Interest-bearing deposits	1	1
Securities purchased under agreements to resell	6,550	13,950
Federal funds sold	8,935	4,605
Trading securities	1,728	888
Available-for-sale securities	16,166	16,651
Held-to-maturity securities	2,254	2,370
Advances	79,757	80,360
Mortgage loans held for portfolio, net	9,546	9,334
Accrued interest receivable	179	195
Derivative assets, net	233	102
Other assets	28	34
Liabilities
Deposits	(1,267)	(1,112)
Federal Home Loan Bank, Consolidated Obligations Fair Value Disclosure	(117,337)	(121,084)
Mandatorily redeemable capital stock	(96)	(206)
Accrued interest payable	(258)	(252)
Derivative liabilities, net	(9)	(1)
Fair Value [Member]
Assets
Cash and due from banks	611	1,029
Interest-bearing deposits	1	1
Securities purchased under agreements to resell	6,550	13,950
Federal funds sold	8,935	4,605
Trading securities	1,728	888
Available-for-sale securities	16,166	16,651
Held-to-Maturity Securities, Fair Value	2,346	2,439
Advances	80,270	80,576
Mortgage loans held for portfolio, net	9,886	9,510
Accrued interest receivable	179	195
Derivative assets, net	233	102
Other assets	28	34
Liabilities
Deposits	(1,267)	(1,112)
Federal Home Loan Bank, Consolidated Obligations Fair Value Disclosure	(118,440)	(121,534)
Mandatorily redeemable capital stock	(96)	(206)
Accrued interest payable	(258)	(252)
Derivative liabilities, net	(9)	(1)
Fair Value, Level 1 [Member]
Assets
Cash and due from banks	611	1,029
Interest-bearing deposits	0	0
Securities purchased under agreements to resell	0	0
Federal funds sold	0	0
Trading securities	0	0
Available-for-sale securities	0	0
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, net	0	0
Other assets	28	34
Liabilities
Deposits	0	0
Federal Home Loan Bank, Consolidated Obligations Fair Value Disclosure	0	0
Mandatorily redeemable capital stock	(96)	(206)
Accrued interest payable	0	0
Derivative liabilities, net	0	0
Fair Value, Level 2 [Member]
Assets
Cash and due from banks	0	0
Interest-bearing deposits	1	1
Securities purchased under agreements to resell	6,550	13,950
Federal funds sold	8,935	4,605
Trading securities	1,728	888
Available-for-sale securities	16,166	16,651
Held-to-Maturity Securities, Fair Value	2,339	2,432
Advances	80,270	80,576
Mortgage loans held for portfolio, net	9,837	9,458
Accrued interest receivable	179	195
Derivative assets, net	71	39
Other assets	0	0
Liabilities
Deposits	(1,267)	(1,112)
Federal Home Loan Bank, Consolidated Obligations Fair Value Disclosure	(118,440)	(121,534)
Mandatorily redeemable capital stock	0	0
Accrued interest payable	(258)	(252)
Derivative liabilities, net	(456)	(202)
Fair Value, 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	0
Available-for-sale securities	0	0
Held-to-Maturity Securities, Fair Value	7	7
Advances	0	0
Mortgage loans held for portfolio, net	49	52
Accrued interest receivable	0	0
Derivative assets, net	0	0
Other assets	0	0
Liabilities
Deposits	0	0
Federal Home Loan Bank, Consolidated Obligations Fair Value Disclosure	0	0
Mandatorily redeemable capital stock	0	0
Accrued interest payable	0	0
Derivative liabilities, net	0	0
Consolidated Obligation Discount Notes [Member] | Reported Value Measurement [Member]
Liabilities
Discount notes	(33,071)	(29,531)
Consolidated Obligation Discount Notes [Member] | Fair Value [Member]
Liabilities
Discount notes	(33,109)	(29,532)
Consolidated Obligation Discount Notes [Member] | Fair Value, Level 1 [Member]
Liabilities
Discount notes	0	0
Consolidated Obligation Discount Notes [Member] | Fair Value, Level 2 [Member]
Liabilities
Discount notes	(33,109)	(29,532)
Consolidated Obligation Discount Notes [Member] | Fair Value, Level 3 [Member]
Liabilities
Discount notes	0	0
Consolidated Obligation Bonds [Member] | Reported Value Measurement [Member]
Liabilities
Bonds, Fair Value	(84,266)	(91,553)
Consolidated Obligation Bonds [Member] | Fair Value [Member]
Liabilities
Bonds, Fair Value	(85,331)	(92,002)
Consolidated Obligation Bonds [Member] | Fair Value, Level 1 [Member]
Liabilities
Bonds, Fair Value	0	0
Consolidated Obligation Bonds [Member] | Fair Value, Level 2 [Member]
Liabilities
Bonds, Fair Value	(85,331)	(92,002)
Consolidated Obligation Bonds [Member] | Fair Value, Level 3 [Member]
Liabilities
Bonds, Fair Value	$ 0	$ 0