Investments in fixed maturity securities - Carrying value by segment (Detail) - USD ($) $ in Millions	Sep. 30, 2015	Dec. 31, 2014
Summary of Investment Holdings [Line Items]
Investments in fixed maturity securities	$ 27,160	$ 27,636
Insurance and Other [Member]
Summary of Investment Holdings [Line Items]
Investments in fixed maturity securities	27,119	27,397
Finance and Financial Products [Member]
Summary of Investment Holdings [Line Items]
Investments in fixed maturity securities	$ 41	$ 239

Amount of debt securities categorized neither as held-to-maturity nor trading.

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 320

-SubTopic 10

-Section 25

-Paragraph 1

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-URI http://asc.fasb.org/extlink&oid=51813488&loc=d3e22054-111558

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

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Reference 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

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Reference 4: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

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Balance Type:	debit
Period Type:	instant