Investments (Schedule Of Other Investments) (Details) - USD ($) $ in Millions	Dec. 31, 2017	Dec. 31, 2016
Schedule of Cost-method Investments [Line Items]
Other investments (cost – $4,417 and $4,270)	$ 4,672	$ 4,519
Other Investments and Securities, at Cost	4,417	4,270
Fair Value
Schedule of Cost-method Investments [Line Items]
Investment Funds	270	251
Limited Partnerships	549	730
Investment Funds Limited Partnerships Partially Owned Investment Companies Total	2,803	2,645
Life Settlement Contracts, Fair Value Method, Face Value	305	248
Policy Loans Investments	244	209
Trading Securities	333	296
Other Other Investments	168	140
Other investments (cost – $4,417 and $4,270)	4,672	4,519
Cost
Schedule of Cost-method Investments [Line Items]
Investment Funds	123	126
Limited Partnerships	441	607
Investment Funds Limited Partnerships Partially Owned Investment Companies Total	2,803	2,645
Life Settlement Contracts, Fair Value Method, Face Value	305	248
Policy Loans Investments	244	209
Trading Securities	333	295
Other Other Investments	168	140
Other Investments and Securities, at Cost	$ 4,417	$ 4,270