Goodwill, Other Intangibles, and Property and Equipment - Components of Depreciation and Amortization Expense (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Depreciation And Amortization By Type [Line Items]
Depreciation and amortization	$ 2,802	$ 3,651	$ 695
Internal-use software
Depreciation And Amortization By Type [Line Items]
Depreciation and amortization	971	850	323
Other property and equipment
Depreciation And Amortization By Type [Line Items]
Depreciation and amortization	276	284	146
Value of business acquired (reported in deferred policy acquisition costs)
Depreciation And Amortization By Type [Line Items]
Depreciation and amortization	28	34	16
Other intangibles
Depreciation And Amortization By Type [Line Items]
Depreciation and amortization	$ 1,527	$ 2,483	$ 210