Fair Value (Fair Value Difference Between Fair Value and Remaining Contractual Principal Balance Outstanding) (Details) - USD ($) $ in Millions		Mar. 31, 2020	Dec. 31, 2019	Mar. 31, 2019	Dec. 31, 2018
Fair Value, Option, Quantitative Disclosures [Line Items]
Fair Value Option, Principal Balance, Advances	[1]	$ 4,162	$ 4,287
Fair Value of Advances Under the Fair Value Option	[1]	4,334	4,370
Fair Value Over/(Under) Principal Balance, Advances	[1]	172	83
Consolidated obligation bonds
Fair Value, Option, Quantitative Disclosures [Line Items]
Fair Value Option, Principal Balance, CO Bonds		250	335
Fair Value of Bonds Under the Fair Value Option		254	337
Fair Value Over/(Under) Principal Balance, CO Bonds		4	2
Advances
Fair Value, Option, Quantitative Disclosures [Line Items]
Fair Value of Advances Under the Fair Value Option		4,334	4,370	$ 5,053	$ 5,133
Consolidated obligation bonds
Fair Value, Option, Quantitative Disclosures [Line Items]
Fair Value of Bonds Under the Fair Value Option		$ 254	$ 337	$ 1,191	$ 2,019

[1] At March 31, 2020, and December 31, 2019, none of these advances were 90 days or more past due or had been placed on nonaccrual status.