Other Comprehensive Income (Loss) (Details) - USD ($) $ in Millions	3 Months Ended				9 Months Ended
	Sep. 30, 2020		Sep. 30, 2019		Sep. 30, 2020		Sep. 30, 2019
Accumulated Other Comprehensive Income (Loss) [Line Items]
Total Other comprehensive income (loss), net of tax	$ 112		$ (102)		$ (148)		$ (33)
Cumulative translation adjustments
Accumulated Other Comprehensive Income (Loss) [Line Items]
Other comprehensive income (loss), pretax	5		(83)		(288)		(33)
Total Other comprehensive income (loss), net of tax	45		(105)		(229)		(54)
Retirement plans and other retiree benefits adjustments
Accumulated Other Comprehensive Income (Loss) [Line Items]
Other comprehensive income (loss), pretax	68		5		110		39
Other comprehensive income (loss), before reclassifications, pretax	53		(14)		55		(15)
Reclassification from AOCI, pretax	15		19		55		54
Other comprehensive income (loss), before reclassifications, net of tax	41		(10)		42		(11)
Reclassification from AOCI, net of tax	13		15		42		41
Total Other comprehensive income (loss), net of tax	54		5		84		30
Gains (losses) on cash flow hedges
Accumulated Other Comprehensive Income (Loss) [Line Items]
Other comprehensive income (loss), pretax	1		5		(2)		(3)
Other comprehensive income (loss), before reclassifications, pretax	(1)		6		2		3
Reclassification from AOCI, pretax	2		(1)		(4)		(6)
Other comprehensive income (loss), before reclassifications, net of tax	(1)		5		1		2
Reclassification from AOCI, net of tax	2		(1)		(3)		(5)
Total Other comprehensive income (loss), net of tax	1		4		(2)		(3)
Total Other comprehensive income (loss)
Accumulated Other Comprehensive Income (Loss) [Line Items]
Other comprehensive income (loss), pretax	74		(73)		(180)		3
Total Other comprehensive income (loss), net of tax	$ 100	[1]	$ (96)	[1]	$ (147)	[2]	$ (27)	[2]

[1] Accumulated other comprehensive income (loss) includes cumulative translation losses of $3,357 at September 30, 2020 ($3,209 at September 30, 2019) and $3,402 at June 30, 2020 ($3,104 at June 30, 2019), respectively, and unrecognized retirement plan and other retiree benefits costs of $1,054 at September 30, 2020 ($1,008 at September 30, 2019) and $1,108 at June 30, 2020 ($1,013 at June 30, 2019), respectively.

[2] Accumulated other comprehensive income (loss) includes cumulative translation losses of $3,357 at September 30, 2020 ($3,209 at September 30, 2019) and $3,128 at December 31, 2019 ($3,155 at December 31, 2018), respectively, and unrecognized retirement plan and other retiree benefits costs of $1,054 at September 30, 2020 ($1,008 at September 30, 2019) and $1,138 at December 31, 2019 ($1,038 at December 31, 2018), respectively.