Other Comprehensive Income (Loss) (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Accumulated Other Comprehensive Income (Loss) [Line Items]
Total Other comprehensive income (loss), net of tax	$ 121	$ 135
Cumulative translation adjustments
Accumulated Other Comprehensive Income (Loss) [Line Items]
Other comprehensive income (loss), Pretax	96	103
Total Other comprehensive income (loss), net of tax	105	125
Retirement plans and other retiree benefits adjustments
Accumulated Other Comprehensive Income (Loss) [Line Items]
Other comprehensive income (loss), before reclassifications, Pretax	0	0
Reclassification from AOCI, Pretax	18	18
Other comprehensive income (loss), Pretax	18	18
Other comprehensive income (loss), before reclassifications, Net of Tax	0	0
Reclassification from AOCI, Net of Tax	14	13
Total Other comprehensive income (loss), net of tax	14	13
Cash flow hedges:
Accumulated Other Comprehensive Income (Loss) [Line Items]
Other comprehensive income (loss), before reclassifications, Pretax	(8)	(13)
Reclassification from AOCI, Pretax	6	(3)
Other comprehensive income (loss), Pretax	(2)	(16)
Other comprehensive income (loss), before reclassifications, Net of Tax	(6)	(8)
Reclassification from AOCI, Net of Tax	5	(2)
Total Other comprehensive income (loss), net of tax	(1)	(10)
Total Other comprehensive income (loss)
Accumulated Other Comprehensive Income (Loss) [Line Items]
Other comprehensive income (loss), Pretax	112	105
Total Other comprehensive income (loss), net of tax	$ 118	$ 128