Revenue (Narrative) (Details) - USD ($) $ in Millions		3 Months Ended
	Mar. 30, 2018	Mar. 30, 2018	Jan. 01, 2018
Revenue from Contract with Customer [Abstract]
Operation-type lease and sales-type lease, revenues		$ 97
Revenue, remaining performance obligation	$ 1,700	1,700
Revenue, remaining performance obligation, expected satisfaction in th next two years, percent	72.00%
Revenue, remaining performance obligation, expected satisfaction in the next 12 months, percent	44.00%
Revenue, remaining performance obligation, expected satisfaction in year two, percent	28.00%
Contract with customer, asset, net	$ 94	94	$ 114
Contract with customer, liability	$ 801	801	$ 783
Contract with customer, liability, revenue recognized		$ 265