Accumulated Other Comprehensive Loss - Changes in Accumulated Other Comprehensive Loss by Component (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2022	Jun. 30, 2021	Jun. 30, 2022	Jun. 30, 2021
Accumulated Other Comprehensive Income Loss [Line Items]
Balance	$ 679	$ 764	$ 634	$ 756
Balance	749	732	749	732
Pension and OPEB liability adjustments
Accumulated Other Comprehensive Income Loss [Line Items]
Balance	(19)	(21)	(17)	(19)
Other comprehensive income (loss) before reclassifications	0	0	0	0
Amounts reclassified from AOCL	(2)	(3)	(5)	(5)
Income tax benefit (expense)	0	1	1	1
Net current period other comprehensive (loss) income	(2)	(2)	(4)	(4)
Balance	(21)	(23)	(21)	(23)
Interest rate swaps
Accumulated Other Comprehensive Income Loss [Line Items]
Balance	(5)	(35)	(24)	(46)
Other comprehensive income (loss) before reclassifications	5	(2)	27	8
Amounts reclassified from AOCL	3	3	6	7
Income tax benefit (expense)	(2)	0	(8)	(3)
Net current period other comprehensive (loss) income	6	1	25	12
Balance	1	(34)	1	(34)
Foreign currency items
Accumulated Other Comprehensive Income Loss [Line Items]
Balance	(32)	(30)	(32)	(24)
Other comprehensive income (loss) before reclassifications	(8)	4	(8)	(2)
Amounts reclassified from AOCL	0	0	0	0
Income tax benefit (expense)	0	0	0	0
Net current period other comprehensive (loss) income	(8)	4	(8)	(2)
Balance	(40)	(26)	(40)	(26)
Accumulated Other Comprehensive (Loss) Income, net of tax
Accumulated Other Comprehensive Income Loss [Line Items]
Balance	(56)	(86)	(73)	(89)
Other comprehensive income (loss) before reclassifications	(3)	2	19	6
Amounts reclassified from AOCL	1	0	1	2
Income tax benefit (expense)	(2)	1	(7)	(2)
Net current period other comprehensive (loss) income	(4)	3	13	6
Balance	$ (60)	$ (83)	$ (60)	$ (83)