Changes in Accumulated Other Comprehensive Income (Loss) by Component (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Balance at beginning of period	$ 1,619
Other comprehensive income (loss), net of tax	(19)	$ (29)	$ (156)
Balance at end of period	181	1,619
Other comprehensive income (loss) attributable to noncontrolling interests, net of tax	14	(10)	(2)
Foreign currency translation adjustment
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Balance at beginning of period	(369)	(395)	(263)
Other comprehensive income (loss) before reclassifications	(26)	23	(134)
Income tax benefit (provision) .	0	3	2
Other comprehensive income (loss), net of tax	(26)	26	(132)
Balance at end of period	(395)	(369)	(395)
Pension and postretirement benefits
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Balance at beginning of period	(342)	(297)	(275)
Other comprehensive income (loss) before reclassifications	(8)	(46)	(47)
Reclassification from other comprehensive income (loss)	(5)	7	22
Other comprehensive income (loss)	(13)	(39)	(25)
Income tax benefit (provision) .	2	(6)	3
Other comprehensive income (loss), net of tax	(11)	(45)	(22)
Balance at end of period	(353)	(342)	(297)
Cash flow hedging instruments
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Balance at beginning of period	0	0	0
Other comprehensive income (loss) before reclassifications	4	1	0
Reclassification from other comprehensive income (loss)	0	(1)	0
Other comprehensive income (loss)	4	0	0
Balance at end of period	4	0	0
Accumulated other comprehensive loss at end of year
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Balance at beginning of period	(711)	(692)	(538)
Balance at end of period	$ (744)	$ (711)	$ (692)