Fair Value Measurements - Nonrecurring Basis (Details) - Fair value on a nonrecurring basis - USD ($)	3 Months Ended	6 Months Ended
Jun. 30, 2021	Jun. 30, 2020	Mar. 31, 2020	Jun. 30, 2021
Assets and Liabilities Measured on Recurring or Nonrecurring Basis
Long-lived asset impairment charges	$ 0	$ 0		$ 0
Adjustment to the carrying value of equity securities using the measurement alternative			$ 22,000,000

Amount of write-down of assets recognized in the income statement. Includes, but is not limited to, losses from tangible assets, intangible assets and goodwill.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 28
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-Section 45
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Amount of unrealized and realized gain (loss) on investment in equity security measured at fair value with change in fair value recognized in net income (FV-NI).

+ References

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-Publisher FASB
-Name Accounting Standards Codification
-Topic 321
-SubTopic 10
-Section 50
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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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