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, 2019	Dec. 31, 2018
Deferred Tax Assets, Net [Abstract]
Deferred Tax Assets, Tax Deferred Expense, Reserves and Accruals	$ 100	$ 86
Deferred Tax Assets Reinsurance Transactions	105	102
Deferred Tax Assets Cash And Invested Assets	0	28
Deferred Tax Assets Investment Income	7	80
Deferred Tax Assets Deferred Acquisition Costs Capitalized For Tax	127	125
Deferred Tax Assets, Operating Loss Carryforwards	330	406
Deferred Tax Assets Deferred Acquisition Costs Capitalized For Financial Reporting	38	33
Deferred Tax Assets, Gross	707	860
Deferred Tax Assets, Valuation Allowance	(236)	(181)
Deferred Tax Assets, Net	471	679
Deferred Tax Liabilities [Abstract]
Deferred Tax Liabilities, Deferred Expense, Deferred Policy Acquisition Cost	797	843
Deferred Tax Liabilities Reinsurance Transactions	1,293	1,152
Deferred Tax Liabilities Cash And Invested Assets	991	346
Deferred Tax Liabilities Investment Income	0	9
Deferred Tax Liabilities, Unrealized Currency Transaction Gains	52	53
Deferred Tax Liabilities, Prepaid Expenses	26	25
Total Deferred Income Tax Liabilities	3,159	2,428
Deferred Tax Liabilities, Net	2,688	1,749
Balance Sheet Presentation Of Deferred Tax Liabilities [Abstract]
Deferred Tax Assets, Other	24	50
Deferred income taxes	2,712	1,799
Deferred Tax Liabilities, Net	$ 2,688	$ 1,749