Disposition of Metropolitan Property and Casualty Insurance Company - Narrative (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Jun. 30, 2021	Jun. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Net investment gains (losses)	$ (84)	$ (20)			$ 1,655	$ (77)
Gain (Loss) on Sale of Business	1,589	709	$ 3,775	$ 4,551	5,364	5,260
Income (Loss) from Continuing Operations before Income Taxes, Noncontrolling Interest	$ 2,042	923			6,820	6,763
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
Gain (Loss) on Sale of Business					1,100
Income (Loss) from Continuing Operations before Income Taxes, Noncontrolling Interest		$ 20			$ 121	$ 254