Derivatives - Rollforward of Interest Rate Swap Balance (Details) - USD ($) $ in Millions	3 Months Ended	9 Months Ended
	Sep. 30, 2020	Sep. 30, 2020
Net Impact Of Derivatives De-Designated As Cash Flow Hedges [Roll Forward]
Beginning balance		$ 6
Ending balance	$ 31	31
Interest Rate | Not Designated as Hedges
Net Impact Of Derivatives De-Designated As Cash Flow Hedges [Roll Forward]
Beginning balance	(7)	0
Change in fair value recognized in other comprehensive income (loss)	5	(2)
Ending balance	$ (2)	$ (2)