Stockholders' Equity - Changes in Accumulated Other Comprehensive Income (Details) - USD ($) $ in Millions		12 Months Ended
	Jan. 01, 2018	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Changes in Accumulated Other Comprehensive Income (Loss)
Beginning balance	$ 4,589	$ 4,589	$ 4,259	$ 5,228
Adoption of new accounting guidance related to reclassification of certain tax effects	45	45	0	0
Ending balance		3,258	4,589	4,259
Accumulated Other Comprehensive Income (Loss)
Changes in Accumulated Other Comprehensive Income (Loss)
Beginning balance	$ (1,287)	(1,287)	(1,807)	(1,504)
Ending balance		(1,677)	(1,287)	(1,807)
Accumulated Foreign Currency Adjustment Including Portion Attributable to Noncontrolling Interest
Changes in Accumulated Other Comprehensive Income (Loss)
Other comprehensive income (loss), before reclassifications, before tax		(308)	294	(251)
Reclassification from accumulated other comprehensive income to income, before tax		5	2	(1)
Other comprehensive income (loss), tax		(25)	110	(25)
Other comprehensive income (loss), net of tax		(328)	406	(277)
Accumulated Defined Benefit Plans Adjustment Including Portion Attributable to Noncontrolling Interest
Changes in Accumulated Other Comprehensive Income (Loss)
Other comprehensive income (loss), before reclassifications, before tax		(64)	96	(67)
Reclassification from accumulated other comprehensive income to income, before tax		41	56	43
Other comprehensive income (loss), tax		6	(38)	(2)
Other comprehensive income (loss), net of tax		$ (17)	$ 114	$ (26)