Fair Value Measurements - Narrative (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2018	Oct. 01, 2017	Sep. 30, 2018	Oct. 01, 2017	Dec. 31, 2017	Jan. 01, 2018
Derivative [Line Items]
Available-for-sale Securities, Equity Securities	$ 697		$ 697		$ 751
Accumulated other comprehensive income on derivatives, after tax	16		$ 16
Reclassification of foreign exchange contracts into earnings, period			next 12 months
Maximum length of time for hedge exposure			18 months
Unrealized gains on equity investments	$ 0	$ 14	$ 0	$ 150
Weighted average interest rate on non-current debt	3.20%		3.20%
Excess of the estimated fair value over the carrying value of debt					2,000
Foreign exchange contracts
Derivative [Line Items]
Collateral Already Posted, Aggregate Fair Value	$ 153		$ 153
Derivative notional amounts outstanding	38,800		38,800		34,500
Cross currency interest rate swaps
Derivative [Line Items]
Derivative notional amounts outstanding	7,300		7,300		2,300
Interest Rate Contract [Member]
Derivative [Line Items]
Derivative Liability, Noncurrent	6		6		9
Derivative notional amounts outstanding	1,100		1,100		1,100
Equity Securities
Derivative [Line Items]
Available-for-sale Securities, Equity Securities	$ 697		697		$ 751
Equity Investments without readily determinable value | Equity Securities
Derivative [Line Items]
Equity, Fair Value Adjustment, Impairment Loss			(31)
Changes in fair value, changes in observable prices			$ 38
Equity Investments with readily determinable value | Equity Securities
Derivative [Line Items]
Unrealized gains on equity investments				$ 269
Retained Earnings | ASU 2016-01 - Financial Instruments
Derivative [Line Items]
Cumulative effect adjustment						$ 232