Derivative and Hedging Activities - Cash Flow Hedges Components of AOCI (Details) - USD ($) $ in Millions		3 Months Ended		9 Months Ended
		Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
AOCI Attributable to Parent, Net of Tax [Roll Forward]
AOCI, after tax, beginning of period				$ 12
Losses reclassified to income, after tax	[1]	$ 7	$ 8	24	$ 26
AOCI, after tax, end of period		36		36
Cash flow hedging
AOCI Attributable to Parent, Net of Tax [Roll Forward]
AOCI, before tax, beginning of period		(28)	(62)	(45)	(80)
AOCI, after tax, beginning of period		29	(5)	12	(23)
Losses reclassified to income, before tax		7	8	24	26
Losses reclassified to income, after tax		7	8	24	26
AOCI, before tax, end of period		(21)	(54)	(21)	(54)
AOCI, after tax, end of period		$ 36	$ 3	$ 36	$ 3

[1] Deferred tax activity incurred in other comprehensive income was offset by a valuation allowance.