Parent Company Financial Information- Additional Information (Details) $ in Billions	Dec. 31, 2019 USD ($)
Subsidiaries
Condensed Financial Statements, Captions [Line Items]
Restricted Assets	$ 12.4

Total assets that cannot be used for operating purposes because of contract or regulatory requirements that are in effect for a period that extends beyond one year.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.17)
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

Name:	us-gaap_OtherRestrictedAssets
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant