Income Tax (Tax Effects of Temporary Differences that Give Rise to Significant Portions of the Deferred Income Tax Asset and Liabilities) (Details) - USD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019
Deferred Tax Assets, Net [Abstract]
Deferred Tax Assets, Tax Deferred Expense, Reserves and Accruals	$ 92	$ 95
Deferred Tax Assets, Operating Loss Carryforwards	254	330
Deferred Tax Assets, Tax Credit Carryforwards	0	38
Deferred Tax Assets, Gross	346	463
Deferred Tax Assets, Valuation Allowance	(251)	(236)
Deferred Tax Assets, Net	95	227
Deferred Tax Liabilities [Abstract]
Deferred Tax Liabilities, Deferred Expense, Deferred Policy Acquisition Cost	775	675
Deferred Tax Liabilities Reinsurance Transactions	1,105	1,208
Deferred Tax Liabilities, Investments	1,043	645
Deferred Tax Liabilities, Undistributed Foreign Earnings	354	308
Deferred Tax Liabilities, Unrealized Currency Transaction Gains	40	52
Deferred Tax Liabilities, Prepaid Expenses	20	26
Total Deferred Income Tax Liabilities	3,339	2,915
Deferred Tax Liabilities, Net	3,244	2,688
Balance Sheet Presentation Of Deferred Tax Liabilities [Abstract]
Deferred Tax Assets, Other	19	24
Deferred income taxes	3,263	2,712
Deferred Tax Liabilities, Net	3,244	2,688
Deferred Tax Liabilities, Other	$ 2	$ 1