Revenue (Narrative) (Details) - USD ($) $ in Millions		3 Months Ended	9 Months Ended
	Sep. 28, 2018	Sep. 28, 2018	Sep. 28, 2018	Jan. 01, 2018
Revenue from Contract with Customer [Abstract]
Operation-type lease and sales-type lease, revenues		$ 115	$ 308
Revenue, remaining performance obligation	$ 1,800	1,800	1,800
Revenue, remaining performance obligation, expected satisfaction in the next 12 months, percent	44.00%
Revenue, remaining performance obligation, expected satisfaction in year two, percent	26.00%
Contract with customer, asset, net	$ 97	97	97	$ 114
Contract with customer, liability	$ 787	787	787	$ 783
Contract with customer, liability, revenue recognized		$ 144	$ 568