Derivative Instruments - Change in Unrealized Gains (Losses) in AOCI (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Balance at beginning of period	$ (194)	$ 388	$ 536	$ 684
Balance at end of period	268	570	268	570
Cash Flow Hedging
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Balance at beginning of period	(5)	7	2	4
Change in fair value, net of tax	2	(2)	(7)	4
Reclassification into earnings, net of tax	2	(1)	4	(4)
Balance at end of period	(1)	4	(1)	4
Net Investment Hedging
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Balance at beginning of period	16	0	(8)	0
Change in fair value, net of tax	(16)	0	8	0
Reclassification into earnings, net of tax	0	0	0	0
Balance at end of period	$ 0	$ 0	$ 0	$ 0