Accumulated Other Comprehensive Loss - Narrative (Details) - USD ($) $ in Millions		3 Months Ended		9 Months Ended
	Jun. 24, 2019	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018	Mar. 31, 2019	Dec. 31, 2018
Accumulated Other Comprehensive Income (Loss) [Line Items]
Estimate of gain related to foreign currency exchange contracts during the next 12 months		$ 3		$ 3
Fair market value adjustment on cash flow hedges, net of income tax benefit of $1 million, $2 million, $46 million and $4 million	$ 183	(4)	$ (6)	(134)	$ (11)
Estimated interest expense related to settled interest rate hedge contracts during the next twelve months		21		21
Foreign currency translation adjustment		28		28
Foreign currency forward exchange contracts | Indian Rupee
Accumulated Other Comprehensive Income (Loss) [Line Items]
Notional amount of derivatives		216		216			$ 202
Total fair value of cash flow hedge derivatives		$ 4		$ 4
Treasury Lock
Accumulated Other Comprehensive Income (Loss) [Line Items]
Derivative liability, notional amount						$ 5,000