Investments in fixed maturity securities - Carrying value by segment (Detail) (USD $) In Millions, unless otherwise specified	Mar. 31, 2014	Dec. 31, 2013
Summary of Investment Holdings [Line Items]
Investments in fixed maturity securities	$ 29,558	$ 29,353
Insurance and Other [Member]
Summary of Investment Holdings [Line Items]
Investments in fixed maturity securities	29,101	28,785
Finance and Financial Products [Member]
Summary of Investment Holdings [Line Items]
Investments in fixed maturity securities	$ 457	$ 568

For an unclassified balance sheet, this item represents investments in debt securities having predetermined or determinable maturity dates.

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

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 03

-Paragraph 1

-Subparagraph a

-Article 7

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 944

-SubTopic 210

-Section S99

-Paragraph 1

-Subparagraph (SX 210.7-03.1(a))

-URI http://asc.fasb.org/extlink&oid=6879938&loc=d3e572229-122910

Name:	us-gaap_MarketableSecuritiesFixedMaturities
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant