Fair Value Measurements - Assets and Liabilities Measured at Fair Value under Certain Conditions (Details) - USD ($) $ in Millions	3 Months Ended
Mar. 31, 2022	Mar. 31, 2021
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Realized investment losses on assets measured at fair value under certain conditions, after-tax	$ 0	$ 0
Realized investment gains on equity securities with no readily determinable fair value

Amount of gain from upward price adjustment on 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 (c)
-URI http://asc.fasb.org/extlink&oid=123583765&loc=SL75117539-209714

Name:	us-gaap_EquitySecuritiesWithoutReadilyDeterminableFairValueUpwardPriceAdjustmentAnnualAmount
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration