Advances (Earlier of Contractual Maturity or Next Call/Put Date) (Details) - USD ($) $ in Millions	Mar. 31, 2020	Dec. 31, 2019	Mar. 31, 2019
Federal Home Loan Bank, Advances, Earlier of Contractual Maturity or Next Call Date, Rolling Year, Par Value [Abstract]
Within 1 year	$ 43,383	$ 39,075
After 1 year through 2 years	20,231	15,731
After 2 years through 3 years	3,782	4,800
After 3 years through 4 years	3,520	2,895
After 4 years through 5 years	4,288	1,447
After 5 years	1,684	1,140
Federal Home Loan Bank, Advances, Earlier of Contractual Maturity or Next Put or Convert Date, Rolling Year, Par Value [Abstract]
Within 1 year	37,531	32,371
After 1 year through 2 years	26,281	22,380
After 2 years through 3 years	3,784	4,847
After 3 years through 4 years	3,520	2,909
After 4 years through 5 years	4,308	1,461
After 5 years	1,464	1,120
Total par value	$ 76,888	$ 65,088	$ 70,175