Fair Value Measurements - Financial Assets and Liabilities Measured at Fair Value on Recurring Basis (Details) - USD ($) $ in Millions	Mar. 31, 2020	Dec. 31, 2019
Foreign currency forward contracts
Derivative Asset:
Foreign currency forward contracts	$ 79
Liabilities
Foreign currency forward contracts		$ 8
Recurring Basis
Investments:
Total assets	1,512	1,566
Recurring Basis \| Foreign currency forward contracts
Derivative Asset:
Foreign currency forward contracts	79
Liabilities
Foreign currency forward contracts		8
Recurring Basis \| Money market funds
Cash equivalents:
Cash equivalents:	322	36
Recurring Basis \| Term deposits
Cash equivalents:
Cash equivalents:	863	865
Investments:
Investments:	184	526
Recurring Basis \| U.S. treasury securities
Cash equivalents:
Cash equivalents:		10
Investments:
Investments:	10
Recurring Basis \| Marketable equity securities
Investments:
Investments:	54	129
Recurring Basis \| Level 1
Investments:
Total assets	386	175
Recurring Basis \| Level 1 \| Foreign currency forward contracts
Derivative Asset:
Foreign currency forward contracts	0
Liabilities
Foreign currency forward contracts		0
Recurring Basis \| Level 1 \| Money market funds
Cash equivalents:
Cash equivalents:	322	36
Recurring Basis \| Level 1 \| Term deposits
Cash equivalents:
Cash equivalents:	0	0
Investments:
Investments:	0	0
Recurring Basis \| Level 1 \| U.S. treasury securities
Cash equivalents:
Cash equivalents:		10
Investments:
Investments:	10
Recurring Basis \| Level 1 \| Marketable equity securities
Investments:
Investments:	54	129
Recurring Basis \| Level 2
Investments:
Total assets	1,126	1,391
Recurring Basis \| Level 2 \| Foreign currency forward contracts
Derivative Asset:
Foreign currency forward contracts	79
Liabilities
Foreign currency forward contracts		8
Recurring Basis \| Level 2 \| Money market funds
Cash equivalents:
Cash equivalents:	0	0
Recurring Basis \| Level 2 \| Term deposits
Cash equivalents:
Cash equivalents:	863	865
Investments:
Investments:	184	526
Recurring Basis \| Level 2 \| U.S. treasury securities
Cash equivalents:
Cash equivalents:		0
Recurring Basis \| Level 2 \| Marketable equity securities
Investments:
Investments:	$ 0	$ 0

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

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-Publisher FASB
-Name Accounting Standards Codification
-Topic 820
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (a)
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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.

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Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
-Section 50
-Paragraph 4B
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Fair value as of the balance sheet date of all foreign currency derivative liabilities not designated as hedging instruments.

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

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Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
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