Derivative Instruments - Change in Unrealized Gains (Losses) in AOCI (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Beginning Balance	$ 766	$ 701	$ 243
Ending Balance	684	766	701
Accumulated net gain (loss) from cash flow hedges attributable to parent
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Beginning Balance	2	2	(1)
Other comprehensive loss before reclassifications	(2)	9	7
Reclassifications from accumulated other comprehensive loss to net earnings	4	(9)	(4)
Ending Balance	$ 4	$ 2	$ 2