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Financial Instruments (Details) - USD ($)	Dec. 31, 2020	Dec. 31, 2019
Short-term investments [Abstract]
Short-term investments reclassified as other assets	$ 10,000,000
Short-term investments	60,000,000	$ 60,000,000
Transfers out of level 2	0
Fair Value of Debt Instruments [Abstract]
Fair value of total debt	31,900,000,000	27,200,000,000
Fair value of total debt in excess (less than) of carrying value	5,100,000,000	$ 2,000,000,000.0
Time Deposits [Member] | Significant Other Observable Inputs (Level 2) [Member]
Short-term investments [Abstract]
Short-term investments	$ 70,000,000

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- Definition

Fair value of total debt in excess of (less than) carrying value.

+ References

No definition available.

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- Definition

Fair value portion of debt instrument payable, including, but not limited to, notes payable and loans payable.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 825
-SubTopic 10
-Section 50
-Paragraph 10
-URI http://asc.fasb.org/extlink&oid=121572278&loc=d3e13433-108611

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- Definition

Amount of transfers of assets measured on a recurring basis out of Level 2 of the fair value hierarchy into Level 1.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 820
-SubTopic 10
-Section 50
-Paragraph 2
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- Definition

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
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-SubTopic 10
-Section 45
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Amount of restricted investment in debt security measured at amortized cost (held-to-maturity).

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 860
-SubTopic 30
-Section 50
-Paragraph 1A
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