Accumulated Other Comprehensive Loss - Amounts reclassified from AOCL (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Accumulated Other Comprehensive Income (Loss) [Line Items]
Other (expense) income, net	$ 5	$ 3	$ 4	$ 6
Income before income taxes	30	229	211	440
Income tax expense	(7)	(48)	(49)	(92)
Net income	23	181	162	348
Reclassified from AOCL | Prior service cost
Accumulated Other Comprehensive Income (Loss) [Line Items]
Other (expense) income, net	3	4	8	7
Reclassified from AOCL | Pension and OPEB liability adjustment
Accumulated Other Comprehensive Income (Loss) [Line Items]
Income before income taxes	3	4	8	7
Income tax expense	(1)	(1)	(2)	(2)
Net income	$ 2	$ 3	$ 6	$ 5