Description of Business, Accounting Policies, and Supplemental Disclosures - Investments (Details) - USD ($) $ in Billions	Dec. 31, 2020	Dec. 31, 2019
Accounting Policies [Abstract]
Equity investments in private companies	$ 2.7	$ 1.5

Amount of investment in equity security without readily determinable fair value.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 321
-SubTopic 10
-Section 50
-Paragraph 3
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=120269885&loc=SL75117539-209714

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Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant