Revenue (Narrative) (Details) - USD ($) $ in Millions		3 Months Ended	6 Months Ended
	Jun. 29, 2018	Jun. 29, 2018	Jun. 29, 2018	Jan. 01, 2018
Revenue from Contract with Customer [Abstract]
Operation-type lease and sales-type lease, revenues		$ 96	$ 193
Revenue, remaining performance obligation	$ 1,700	1,700	1,700
Revenue, remaining performance obligation, expected satisfaction in the next 12 months, percent	45.00%
Revenue, remaining performance obligation, expected satisfaction in year two, percent	27.00%
Contract with customer, asset, net	$ 98	98	98	$ 114
Contract with customer, liability	$ 791	$ 791	791	$ 783
Contract with customer, liability, revenue recognized			$ 424