Derivative and Hedging Activities - Cash Flow Hedges Components of AOCI (Details) - USD ($) $ in Millions		3 Months Ended
		Mar. 31, 2020	Mar. 31, 2019
AOCI Attributable to Parent, Net of Tax [Roll Forward]
AOCI, after tax, beginning of period		$ 12
Losses reclassified to income, after tax	[1]	9	$ 10
AOCI, after tax, end of period		21
Cash flow hedging
AOCI Attributable to Parent, Net of Tax [Roll Forward]
AOCI, before tax, beginning of period		(45)	(80)
AOCI, after tax, beginning of period		12	(23)
Losses reclassified to income, before tax		9
Losses reclassified to income, after tax		9
Losses reclassified to income, before tax			10
Losses reclassified to income, after tax			10
AOCI, before tax, end of period		(36)	(70)
AOCI, after tax, end of period		$ 21	$ (13)

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