Disposition of Metropolitan Property and Casualty Insurance Company - Narrative (Details) - USD ($) $ in Millions	3 Months Ended				6 Months Ended
	Jun. 30, 2021	Mar. 31, 2021	Jun. 30, 2020	Mar. 31, 2020	Jun. 30, 2021	Jun. 30, 2020
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Net investment gains (losses)	$ 1,605		$ 231		$ 1,739	$ (57)
Gain (Loss) on Sale of Business	3,412	$ 363	150	$ 4,401	3,775	4,551
Income (Loss) from Continuing Operations before Income Taxes, Noncontrolling Interest	4,487		197		4,778	5,840
Metropolitan Property And Casualty Insurance Company
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Proceeds from divestiture of business.	3,900
Net investment gains (losses)	1,400				1,400
Gain (Loss) on Sale of Business	$ 1,100				1,100
Income (Loss) from Continuing Operations before Income Taxes, Noncontrolling Interest			$ 119		$ 121	$ 234