Revenue (Narrative) (Details) - USD ($) $ in Millions		3 Months Ended		6 Months Ended
	Jun. 28, 2019	Jun. 28, 2019	Jun. 29, 2018	Jun. 28, 2019	Jun. 29, 2018	Dec. 31, 2018
Revenue from Contract with Customer [Abstract]
Revenue, OTLs and STLs		$ 106	$ 96	$ 213	$ 193
Revenue, remaining performance obligation	$ 2,000	2,000		2,000
Revenue, remaining performance obligation, expected satisfaction in next 12 months, percent	40.00%
Revenue, remaining performance obligation, expected satisfaction in subsequent 12 months, percent	25.00%
Contract with customer, asset, net	$ 85	85		85		$ 82
Contract with customer, liability	$ 822	$ 822		822		$ 799
Contract with customer, liability, revenue recognized				$ 442	$ 424