Other Comprehensive Income (Loss) (Details) - USD ($) $ in Millions		3 Months Ended
		Mar. 31, 2019	Mar. 31, 2018
Accumulated Other Comprehensive Income (Loss) [Line Items]
Total Other comprehensive income (loss), net of tax		$ 33	$ 121
Cumulative translation adjustments
Accumulated Other Comprehensive Income (Loss) [Line Items]
Other comprehensive income (loss), Pretax		27	96
Total Other comprehensive income (loss), net of tax		21	105
Retirement plans and other retiree benefits adjustments
Accumulated Other Comprehensive Income (Loss) [Line Items]
Other comprehensive income (loss), before reclassifications, Pretax		(1)	0
Reclassification from AOCI, Pretax		17	18
Other comprehensive income (loss), Pretax		16	18
Other comprehensive income (loss), before reclassifications, Net of Tax		(1)	0
Reclassification from AOCI, Net of Tax		13	14
Total Other comprehensive income (loss), net of tax		12	14
Gains (losses) on cash flow hedges
Accumulated Other Comprehensive Income (Loss) [Line Items]
Other comprehensive income (loss), before reclassifications, Pretax		(2)
Reclassification from AOCI, Pretax		(4)
Other comprehensive income (loss), Pretax		(6)
Other comprehensive income (loss), before reclassifications, Net of Tax		(2)
Reclassification from AOCI, Net of Tax		(3)
Total Other comprehensive income (loss), net of tax		(5)
Gains (losses) on cash flow hedges
Accumulated Other Comprehensive Income (Loss) [Line Items]
Other comprehensive income (loss), before reclassifications, Pretax			(8)
Reclassification from AOCI, Pretax			6
Other comprehensive income (loss), Pretax			(2)
Other comprehensive income (loss), before reclassifications, Net of Tax			(6)
Reclassification from AOCI, Net of Tax			5
Total Other comprehensive income (loss), net of tax			(1)
Total Other comprehensive income (loss)
Accumulated Other Comprehensive Income (Loss) [Line Items]
Other comprehensive income (loss), Pretax		37	112
Total Other comprehensive income (loss), net of tax	[1]	$ 28	$ 118

[1] Accumulated other comprehensive income (loss) includes cumulative translation losses of $3,134 at March 31, 2019 ($2,832 at March 31, 2018) and $3,155 at December 31, 2018 ($2,927 at December 31, 2017), respectively, and unrecognized retirement plan and other retiree benefits costs of $1,026 at March 31, 2019 ($1,062 at March 31, 2018) and $1,038 at December 31, 2018 ($923 at December 31, 2017), respectively.