Derivative and Hedging Activities - Cash Flow Hedges Components of AOCI (Details) - USD ($) $ in Millions		3 Months Ended		6 Months Ended
		Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 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]	$ 8	$ 8	17	$ 18
AOCI, after tax, end of period		29		29
Cash flow hedging
AOCI Attributable to Parent, Net of Tax [Roll Forward]
AOCI, before tax, beginning of period		(36)	(70)	(45)	(80)
AOCI, after tax, beginning of period		21	(13)	12	(23)
Losses reclassified to income, before tax		8	8	17	18
Losses reclassified to income, after tax		8	8	17	18
AOCI, before tax, end of period		(28)	(62)	(28)	(62)
AOCI, after tax, end of period		$ 29	$ (5)	$ 29	$ (5)

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