Revenue (Narrative) (Details) - USD ($) $ in Millions		3 Months Ended		9 Months Ended
	Sep. 27, 2019	Sep. 27, 2019	Sep. 28, 2018	Sep. 27, 2019	Sep. 28, 2018	Dec. 31, 2018
Revenue from Contract with Customer [Abstract]
Revenue, OTLs and STLs		$ 108	$ 115	$ 321	$ 308
Revenue, remaining performance obligation	$ 2,000	2,000		2,000
Revenue, remaining performance obligation, expected satisfaction in next 12 months, percent	39.00%
Revenue, remaining performance obligation, expected satisfaction in subsequent 12 months, percent	25.00%
Contract with customer, asset, net	$ 77	77		77		$ 82
Contract with customer, liability	$ 801	$ 801		801		$ 799
Contract with customer, liability, revenue recognized				$ 544	$ 568