Commitments and Contingencies (Details) - CNA Financial [Member] $ in Millions	12 Months Ended
Dec. 31, 2020 USD ($)
Commitments and Contingencies [Abstract]
Potential amount of future payments under guarantees	$ 1,700
Insurance Premiums [Member] \| Experience Rating Calculation Discrepancies [Member]
Commitments and Contingencies [Abstract]
Loss contingency	$ 14

Maximum potential amount of future payments (undiscounted) the guarantor could be required to make under the guarantee or each group of similar guarantees before reduction for potential recoveries under recourse or collateralization provisions.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 460
-SubTopic 10
-Section 50
-Paragraph 4
-Subparagraph (b)(1)
-URI http://asc.fasb.org/extlink&oid=121555522&loc=d3e12069-110248

Name:	us-gaap_GuaranteeObligationsMaximumExposure
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant