Investments (Schedule Of Investments In Partially-Owned Insurance Companies) (Details) - USD ($) $ in Millions	Dec. 31, 2017	Dec. 31, 2016
Investment [Line Items]
Carrying Value	$ 662	$ 666
Issued Share Capital	1,942	1,888
Huatai Group \| CHINA
Investment [Line Items]
Carrying Value	438	447
Issued Share Capital	$ 616	$ 624
Ownership Percentage	20.00%	20.00%
Huatai Life Insurance Company \| CHINA
Investment [Line Items]
Carrying Value	$ 105	$ 99
Issued Share Capital	$ 495	$ 428
Ownership Percentage	20.00%	20.00%
Freisenbruch-Meyer \| Bermuda
Investment [Line Items]
Carrying Value	$ 9	$ 8
Issued Share Capital	$ 0	$ 5
Ownership Percentage	40.00%	40.00%
Russian Reinsurance Company \| Russia
Investment [Line Items]
Carrying Value	$ 2	$ 2
Issued Share Capital	$ 4	$ 4
Ownership Percentage	23.00%	23.00%
ABR Reinsurance Capital Holdings Ltd. [Member] \| Bermuda
Investment [Line Items]
Carrying Value	$ 93	$ 97
Issued Share Capital	$ 800	$ 800
Ownership Percentage	11.00%	11.00%
Chubb Arabia Cooperative Insurance Company [Member] \| Saudi Arabia
Investment [Line Items]
Carrying Value	$ 15	$ 13
Issued Share Capital	$ 27	$ 27
Ownership Percentage	30.00%	30.00%

Line items represent reporting concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Regulation S-X (SX)
-Number 210
-Article 12
-Section 12
-Sentence Column A

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- Definition

Cost to investors of each class of capital shares or other capital units.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 946
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.6-04.16(b)(1))
-URI http://asc.fasb.org/extlink&oid=6488278&loc=d3e603758-122996

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The percentage of ownership of common stock or equity participation in the investee accounted for under the equity method of accounting.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 323
-SubTopic 10
-Section 50
-Paragraph 3
-Subparagraph (a)(1)
-URI http://asc.fasb.org/extlink&oid=66011266&loc=d3e33918-111571

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Total investments in (A) an entity in which the entity has significant influence, but does not have control, (B) subsidiaries that are not required to be consolidated and are accounted for using the equity and or cost method, and (C) an entity in which the reporting entity shares control of the entity with another party or group. Includes long-term advances receivable from a party that is affiliated with the reporting entity by means of direct or indirect ownership.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.12)
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

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