Fair Value (Narrative) (Details) - USD ($) $ in Billions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Carrying value of FHLB and FRB stock	$ 1.1	$ 1.6
Distributions received over the life of the partnerships from liquidation of the underlying investments by the investee, period	10 years
Sensitivity analysis of fair value, inputs change for fair value	0.10%