Accumulated Other Comprehensive Income - Summary of Changes in Balances for Each Component of Accumulated Other Comprehensive Income (Details) - USD ($) $ in Millions	3 Months Ended					9 Months Ended
	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Sep. 30, 2019	Mar. 31, 2019	Sep. 30, 2020	Sep. 30, 2019
Accumulated Other Comprehensive Income Loss [Line Items]
Beginning balance	$ 1,484	$ 1,370	$ (818)	$ (910)	$ (1,027)	$ (818)	$ (1,027)
Other comprehensive income (loss)	(1)	1	(2)		(1)
Ending balance	1,551	1,484	1,370	(798)	(999)	1,551	(798)
Currency Translation Adjustments
Accumulated Other Comprehensive Income Loss [Line Items]
Balance as of beginning of period	(7)		(6)	(7)	(7)	(6)	(7)
Currency translation adjustments						(1)
Other comprehensive income (loss)						(1)
Balance as of end of period	(7)	(7)		(7)		(7)	(7)
Employee Benefit Plans
Accumulated Other Comprehensive Income Loss [Line Items]
Balance as of beginning of period	11		11	16	14	11	14
Adoption of new accounting principle							3
Amortization of actuarial gain	(1)			(1)		(1)	(2)
Tax benefit on reclassifications				1			1
Other comprehensive income (loss)	(1)					(1)	(1)
Balance as of end of period	10	11		16		10	16
Accumulated Other Comprehensive Income
Accumulated Other Comprehensive Income Loss [Line Items]
Beginning balance	4	3	5	9	7	5	7
Adoption of new accounting principle					3		3
Other comprehensive income (loss)	(1)	1	(2)		(1)	(2)	(1)
Ending balance	$ 3	$ 4	$ 3	$ 9	$ 9	$ 3	$ 9