Other Financial Data - Accumulated Other Comprehensive Loss (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Oct. 01, 2016	Sep. 30, 2017	Oct. 01, 2016
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Balance at beginning of period			$ (952)
Total other comprehensive income (loss), net of tax	$ 73	$ (43)	191	$ (65)
Balance at end of period	(818)		(818)
Total Accumulated other comprehensive loss	(818)		(952)
Accumulated Other Comprehensive Income (Loss)
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Balance at beginning of period			(2,317)
Total other comprehensive income (loss), net of tax			191
Balance at end of period	(2,126)	(1,931)	(2,126)	(1,931)
Total Accumulated other comprehensive loss	(2,126)	(1,931)	(2,317)	(1,931)
Foreign Currency Translation Adjustments:
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Balance at beginning of period	(413)	(351)	(494)	(266)
Other comprehensive income (loss) before reclassification adjustment	49	(47)	133	(131)
Tax (expense) benefit	(3)	(2)	(6)	(3)
Total other comprehensive income (loss), net of tax	46	(49)	127	(134)
Balance at end of period	(367)	(400)	(367)	(400)
Total Accumulated other comprehensive loss	(413)	(351)	(494)	(266)
Available-for-Sale Securities:
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Balance at beginning of period	4	0	0	(3)
Other comprehensive income (loss) before reclassification adjustment	1	1	8	(1)
Tax (expense) benefit	0	0	(3)	1
Other comprehensive income before reclassification adjustment, net of tax	1	1	5	0
Reclassification adjustment before tax	0	0	0	6
Tax expense (benefit)	0	0	0	(2)
Reclassification adjustment after tax	0	0	0	4
Total other comprehensive income (loss), net of tax	1	1	5	4
Balance at end of period	5	1	5	1
Total Accumulated other comprehensive loss	4	0	0	(3)
Defined Benefit Plans:
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Balance at beginning of period	(1,790)	(1,537)	(1,823)	(1,597)
Other comprehensive income (loss) before reclassification adjustment	(4)	0	(15)	53
Tax (expense) benefit	0	0	0	(16)
Other comprehensive income before reclassification adjustment, net of tax	(4)	0	(15)	37
Tax expense (benefit)	(4)	(1)	(9)	8
Reclassification adjustment after tax	30	5	74	28
Total other comprehensive income (loss), net of tax	26	5	59	65
Balance at end of period	(1,764)	(1,532)	(1,764)	(1,532)
Total Accumulated other comprehensive loss	(1,790)	(1,537)	(1,823)	(1,597)
Reclassification adjustment - Actuarial net losses into Selling, general, and administrative expenses
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Reclassification adjustment before tax	17	13	49	40
Reclassification adjustment - Prior service benefits into Selling, general, and administrative expenses
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Reclassification adjustment before tax	(4)	(7)	(12)	(20)
Reclassification adjustment - Non-U.S. pension settlement loss into Other charges
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Reclassification adjustment before tax	$ 21	$ 0	$ 46	$ 0