Advances (Redemption Terms) (Details) - USD ($) $ in Millions		Dec. 31, 2019	Dec. 31, 2018
Federal Home Loan Bank Advances, Maturities [Abstract]
Within 1 year		$ 32,351	$ 42,285
After 1 year through 2 years		22,380	13,662
After 2 years through 3 years		4,847	11,238
After 3 years through 4 years		2,909	2,409
After 4 years through 5 years		1,461	2,815
After 5 years		1,140	1,086
Total par value		65,088	73,495
Valuation adjustments for hedging activities		203	(32)
Valuation adjustments under fair value option	[1]	83	(29)
Total		$ 65,374	$ 73,434
Federal Home Loan Bank Advances, Weighted Average Interest Rate [Abstract]
Within 1 year		1.91%	2.40%
After 1 year through 2 years		2.15%	2.57%
After 2 years through 3 years		2.08%	2.70%
After 3 years through 4 years		2.97%	2.45%
After 4 years through 5 years		2.32%	2.99%
After 5 years		2.96%	3.23%
Total par value		2.08%	2.51%

[1] At December 31, 2019 and 2018, none of these advances were 90 days or more past due or had been placed on nonaccrual status.