Derivatives and Hedging Activities (Derivatives in Statement of Income) (Details) - USD ($) $ in Millions		3 Months Ended
		Mar. 31, 2020	Mar. 31, 2019
Derivative Instruments, Gain (Loss) [Line Items]
Advances		$ 279	$ 498
AFS securities		51	79
Bonds		(276)	(455)
Advances | Interest Income [Member] | Interest Rate Contract [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Change in Unrealized Gain (Loss) on Fair Value Hedging Instruments	[1]	(651)	(82)
Change in Unrealized Gain (Loss) on Hedged Item in Fair Value Hedge		610	103
Gain (loss) on Fair Value Hedges Recognized in Net Interest Income		(41)	21
Available-for-sale Securities | Interest Income [Member] | Interest Rate Contract [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Change in Unrealized Gain (Loss) on Fair Value Hedging Instruments	[1]	(968)	(128)
Change in Unrealized Gain (Loss) on Hedged Item in Fair Value Hedge		893	117
Gain (loss) on Fair Value Hedges Recognized in Net Interest Income		(75)	(11)
Consolidated Obligations, Bonds | Interest Expense [Member] | Interest Rate Contract [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Change in Unrealized Gain (Loss) on Fair Value Hedging Instruments	[1]	26	19
Change in Unrealized Gain (Loss) on Hedged Item in Fair Value Hedge		(23)	(28)
Gain (loss) on Fair Value Hedges Recognized in Net Interest Income		$ 3	$ (9)

[1] .