Special Charges - Restructuring reserve activity and total expected cash outlay (Details) - USD ($) $ in Millions	3 Months Ended	9 Months Ended
	Oct. 01, 2016	Oct. 01, 2016
Special Charges
Provision	$ 79	$ 79
Cash paid	(2)	(2)
End of period	77	77
Minimum
Special Charges
Total expected cash outlay for restructuring activities	100
Maximum
Special Charges
Total expected cash outlay for restructuring activities	120
Severance Costs
Special Charges
Provision	66	66
Cash paid	(2)	(2)
End of period	64	64
Contract Terminations and Other
Special Charges
Provision	13	13
End of period	$ 13	$ 13