Other Financial Data - Accumulated Other Comprehensive Loss (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2018	Apr. 01, 2017
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Balance at beginning of period	$ (1,727)
Total other comprehensive income, net of tax	54	$ 53
Balance at end of period	(1,539)
Total Accumulated other comprehensive loss	(1,727)
Accumulated Other Comprehensive Income (Loss)
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Balance at beginning of period	(2,562)
Total other comprehensive income, net of tax	54
Balance at end of period	(2,508)	(2,264)
Total Accumulated other comprehensive loss	(2,562)	(2,264)
Foreign Currency Translation Adjustments:
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Balance at beginning of period	(353)	(494)
Other comprehensive income before reclassification adjustment	51	37
Tax expense	(3)	(3)
Total other comprehensive income, net of tax	48	34
Balance at end of period	(305)	(460)
Total Accumulated other comprehensive loss	(353)	(494)
Available-for-Sale Securities:
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Balance at beginning of period	6	0
Reclassification adjustment before tax	(8)	0
Tax expense (benefit)	2	0
Total other comprehensive income, net of tax	(6)	0
Balance at end of period	0	0
Total Accumulated other comprehensive loss	6	0
Defined Benefit Plans:
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Balance at beginning of period	(2,215)	(1,823)
Tax expense (benefit)	(2)	(2)
Total other comprehensive income, net of tax	12	19
Balance at end of period	(2,203)	(1,804)
Total Accumulated other comprehensive loss	(2,215)	(1,823)
Reclassification adjustment - Actuarial net losses into Other income (expense)
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Reclassification adjustment before tax	18	16
Reclassification adjustment - Prior service benefits into Other income (expense)
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Reclassification adjustment before tax	(4)	(4)
Reclassification adjustment - Non-U.S. pension settlement loss into Other income (expense)
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Reclassification adjustment before tax	$ 0	$ 9