Income Taxes - Summary of the Components of Our Provision for Income Taxes (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017		Dec. 31, 2016
Current income tax expense:
Federal	$ 37	$ 93		$ 38
State	12	1		2
Foreign	17	6		11
Current income tax expense	66	100		51
Deferred income tax expense (benefit):
Federal	(10)	25		(12)
State	(1)	2		(3)
Foreign	5	2		(5)
Deferred income tax expense (benefit):	(6)	29		(20)
Provision for income taxes	$ 60	$ 129	[1]	$ 31

[1] The year ended December 31, 2017 reflects $67 million of Transition Tax and $6 million of tax expense recorded due to the remeasurement of net deferred tax assets related to the 2017 Tax Act enacted on December 22, 2017. Refer to “Note 11: Income Taxes” for further information.