Accumulated Other Comprehensive Income (Loss) (Details) - USD ($) $ in Millions		3 Months Ended
	Jan. 01, 2018	Mar. 31, 2019	Mar. 31, 2018
Changes in Accumulated Other Comprehensive Income [Roll Forward]
Beginning balance	$ 4,589	$ 3,258	$ 4,589
Adoption of new accounting guidance related to reclassification of certain tax effects	(45)	0	(45)
Ending balance		3,200	4,163
Accumulated Other Comprehensive Income Attributable to Parent
Changes in Accumulated Other Comprehensive Income [Roll Forward]
Beginning balance	$ (1,287)	(1,677)	(1,287)
Ending balance		(1,642)	(1,240)
Accumulated Defined Benefit Plans Adjustment Attributable to Parent
Changes in Accumulated Other Comprehensive Income [Roll Forward]
Other comprehensive income (loss), adjustments during the period		0	1
Other comprehensive income (loss), adjustments reclassified to income		5	10
Income taxes		(1)	(2)
Other comprehensive income (loss), net of tax		4	9
Accumulated Foreign Currency Adjustment Attributable to Parent
Changes in Accumulated Other Comprehensive Income [Roll Forward]
Other comprehensive income (loss), adjustments during the period		43	69
Income taxes		(12)	14
Other comprehensive income (loss), net of tax		$ 31	$ 83