Accumulated Other Comprehensive Loss - Schedule of Accumulated Other Comprehensive Income (Loss) (Details) - USD ($) $ in Millions		3 Months Ended		6 Months Ended
	Jan. 01, 2019	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Stockholders' equity attributable to parent, beginning balance	$ 9,852			$ 9,852
Reclassification of tax effects per ASU 2018-02	0
Stockholders' equity attributable to parent, ending balance		$ 10,090		10,090
Foreign currency translation [Member]
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Stockholders' equity attributable to parent, beginning balance	(616)	(607)	$ (307)	(616)	$ (365)
Other comprehensive income/(loss) before reclassifications		(19)	(199)	(10)	(141)
Amounts reclassified from accumulated other comprehensive income/(loss) (net of income tax)		0	0	0	0
Net current-period other comprehensive income/(loss)		(19)	(199)	(10)	(141)
Stockholders' equity attributable to parent, ending balance		(626)	(506)	(626)	(506)
Foreign currency translation [Member] | Accounting Standards Update 2018-02 [Member]
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Reclassification of tax effects per ASU 2018-02				0	0
Gains and losses on cash flow hedges [Member]
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Stockholders' equity attributable to parent, beginning balance	(8)	3	9	(8)	(10)
Other comprehensive income/(loss) before reclassifications		(7)	(20)	(1)	(11)
Amounts reclassified from accumulated other comprehensive income/(loss) (net of income tax)		0	6	5	16
Net current-period other comprehensive income/(loss)		(7)	(14)	4	5
Stockholders' equity attributable to parent, ending balance		(4)	(5)	(4)	(5)
Gains and losses on cash flow hedges [Member] | Accounting Standards Update 2018-02 [Member]
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Reclassification of tax effects per ASU 2018-02				0	0
Defined pension and post-retirement benefit costs [Member]
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Stockholders' equity attributable to parent, beginning balance	(1,337)	(1,370)	(1,132)	(1,337)	(1,138)
Other comprehensive income/(loss) before reclassifications		3	35	4	34
Amounts reclassified from accumulated other comprehensive income/(loss) (net of income tax)		4	3	6	10
Net current-period other comprehensive income/(loss)		7	38	(26)	44
Stockholders' equity attributable to parent, ending balance		(1,363)	(1,094)	(1,363)	(1,094)
Defined pension and post-retirement benefit costs [Member] | Accounting Standards Update 2018-02 [Member]
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Reclassification of tax effects per ASU 2018-02	36			(36)	0
AOCL [Member]
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Stockholders' equity attributable to parent, beginning balance	$ (1,961)	(1,974)	(1,430)	(1,961)	(1,513)
Other comprehensive income/(loss) before reclassifications		(23)	(184)	(7)	(118)
Amounts reclassified from accumulated other comprehensive income/(loss) (net of income tax)		4	9	11	26
Net current-period other comprehensive income/(loss)		(19)	(175)	(32)	(92)
Stockholders' equity attributable to parent, ending balance		$ (1,993)	$ (1,605)	(1,993)	(1,605)
AOCL [Member] | Accounting Standards Update 2018-02 [Member]
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Reclassification of tax effects per ASU 2018-02				$ (36)	$ 0