Investments (Schedule Of Impaired Mortgage Loans) (Details) $ in Millions	Dec. 31, 2017 USD ($) item	Dec. 31, 2016 USD ($) item	Dec. 31, 2015 USD ($)	Dec. 31, 2014 USD ($)
Information about impaired mortgage loans on real estate
Number of impaired mortgage loans on real estate \| item	3	2
Principal balance of impaired mortgage loans on real estate	$ 11	$ 7
Valuation allowance associated with impaired mortgage loans on real estate	(3)	(2)	$ (2)	$ (3)
Carrying value of impaired mortgage loans on real estate	$ 8	$ 5

The reserve to cover probable credit losses related to specifically identified fixed maturity real estate loans as well as probable credit losses inherent in the remainder of that loan portfolio.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 310
-Section 45
-Paragraph 4
-URI http://asc.fasb.org/extlink&oid=82921503&loc=d3e21338-158488

Name:	us-gaap_AllowanceForLoanAndLeaseLossesRealEstate
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant