Commitments and Contingencies (Details) $ in Millions		Jun. 30, 2019 USD ($) letter_of_credit	Dec. 31, 2018 USD ($) letter_of_credit
Standby Letters of Credit [Member]
Loss Contingencies [Line Items]
Number Of Outstanding Standby Letters Of Credit Renewable Annually | letter_of_credit		14	14
Standby Letters Of Credit Issued Renewable Annually		$ 36	$ 37
Fair Value Disclosure, Off-balance Sheet Risks, Face Amount, Expiring Within One Year	[1]	9,672	12,334
Fair Value Disclosure, Off-balance Sheet Risks, Face Amount, Expiring After One Year		15,531	17,974
Fair Value Disclosure, Off-balance Sheet Risks, Face Amount, Liability		25,203	30,308
Commitments to Fund Additional Advances [Member]
Loss Contingencies [Line Items]
Fair Value Disclosure, Off-balance Sheet Risks, Face Amount, Expiring Within One Year		361	48
Fair Value Disclosure, Off-balance Sheet Risks, Face Amount, Expiring After One Year		0	0
Fair Value Disclosure, Off-balance Sheet Risks, Face Amount, Liability		361	48
Unsettled Consolidated Obligation Bonds [Member]
Loss Contingencies [Line Items]
Fair Value Disclosure, Off-balance Sheet Risks, Face Amount, Expiring Within One Year	[2]	25	640
Fair Value Disclosure, Off-balance Sheet Risks, Face Amount, Expiring After One Year	[2]	0	0
Fair Value Disclosure, Off-balance Sheet Risks, Face Amount, Liability		25	640
Unsettled Discount Notes [Member]
Loss Contingencies [Line Items]
Fair Value Disclosure, Off-balance Sheet Risks, Face Amount, Expiring Within One Year	[2]	0	750
Fair Value Disclosure, Off-balance Sheet Risks, Face Amount, Expiring After One Year	[2]	0	0
Fair Value Disclosure, Off-balance Sheet Risks, Face Amount, Liability		$ 0	$ 750

[1] “Expire Within One Year” includes 14 standby letters of credit for a total of $36 and $37 as of June 30, 2019 and December 31, 2018, respectively, which have no stated maturity date and are subject to renewal on an annual basis.

[2] Expiration is based on settlement period rather than underlying contractual maturity of consolidated obligations.