Fair Value Measurements - Financial Assets and Liabilities Measured at Fair Value on Recurring Basis (Details) - Recurring Basis - USD ($) $ in Millions	Sep. 30, 2019	Dec. 31, 2018
Investments:
Total assets	$ 1,830	$ 828
Time deposits
Investments:
Investments:	647	28
Marketable equity securities
Investments:
Investments:	109	119
Foreign currency forward contracts
Derivative Asset:
Foreign currency forward contracts	20	22
Money market funds
Cash equivalents:
Cash equivalents:	26	35
Time deposits
Cash equivalents:
Cash equivalents:	1,028	624
Level 1
Investments:
Total assets	135	154
Level 1 \| Time deposits
Investments:
Investments:	0	0
Level 1 \| Marketable equity securities
Investments:
Investments:	109	119
Level 1 \| Foreign currency forward contracts
Derivative Asset:
Foreign currency forward contracts	0	0
Level 1 \| Money market funds
Cash equivalents:
Cash equivalents:	26	35
Level 1 \| Time deposits
Cash equivalents:
Cash equivalents:	0	0
Level 2
Investments:
Total assets	1,695	674
Level 2 \| Time deposits
Investments:
Investments:	647	28
Level 2 \| Marketable equity securities
Investments:
Investments:	0	0
Level 2 \| Foreign currency forward contracts
Derivative Asset:
Foreign currency forward contracts	20	22
Level 2 \| Money market funds
Cash equivalents:
Cash equivalents:	0	0
Level 2 \| Time deposits
Cash equivalents:
Cash equivalents:	$ 1,028	$ 624

Fair value portion of probable future economic benefits obtained or controlled by an entity as a result of past transactions or events.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 820
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=117815213&loc=d3e19207-110258

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Fair value portion of currency on hand as well as demand deposits with banks or financial institutions. Includes other kinds of accounts that have the general characteristics of demand deposits. Also includes short-term, highly liquid investments that are both readily convertible to known amounts of cash and so near their maturity that they present insignificant risk of changes in value because of changes in interest rates.

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Fair value as of the balance sheet date of all foreign currency derivative assets not designated as hedging instruments.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
-Section 50
-Paragraph 4B
-Subparagraph (c)(2)
-URI http://asc.fasb.org/extlink&oid=109980867&loc=SL5624163-113959

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- Definition

Fair value portion of investment securities, including, but not limited to, marketable securities, derivative financial instruments, and investments accounted for under the equity method.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 820
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (a)
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