Investments (Schedule of Held-to-Maturity Securities) (Details) - Short-term Investments [Member] - USD ($) $ in Millions	Jun. 30, 2020	Dec. 31, 2019
Schedule of Held-to-maturity Securities [Line Items]
Held-to-maturity investment securities	$ 130	$ 287
Debt Securities, Held-to-maturity, Accumulated Unrecognized Gain	1	0
Debt Securities, Held-to-maturity, Accumulated Unrecognized Loss	0	0
Fair Value	131	287
Corporate And Other Debt Securities [Member]
Schedule of Held-to-maturity Securities [Line Items]
Held-to-maturity investment securities	56	101
Debt Securities, Held-to-maturity, Accumulated Unrecognized Gain	0	0
Debt Securities, Held-to-maturity, Accumulated Unrecognized Loss	0	0
Fair Value	56	101
Commercial Paper [Member]
Schedule of Held-to-maturity Securities [Line Items]
Held-to-maturity investment securities	74	186
Debt Securities, Held-to-maturity, Accumulated Unrecognized Gain	1	0
Debt Securities, Held-to-maturity, Accumulated Unrecognized Loss	0	0
Fair Value	$ 75	$ 186

Amount of accumulated unrecognized gain on investment in debt security measured at amortized cost (held-to-maturity).

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 50
-Paragraph 5
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=118939692&loc=d3e27232-111563

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- Definition

Amount of accumulated unrealized loss on investment in debt security measured at amortized cost (held-to-maturity).

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 50
-Paragraph 5
-Subparagraph (c)
-URI http://asc.fasb.org/extlink&oid=118939692&loc=d3e27232-111563

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Amount of investment in debt security measured at amortized cost (held-to-maturity), classified as current.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 45
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=118954083&loc=d3e26626-111562

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Fair value of investment in debt security measured at amortized cost (held-to-maturity).

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 50
-Paragraph 5
-Subparagraph (aa)
-URI http://asc.fasb.org/extlink&oid=118939692&loc=d3e27232-111563

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Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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No definition available.

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