Investment gains/losses (Detail) (USD $) In Millions, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012
Gain (Loss) on Investments [Line Items]
OTTI losses			$ (85)	$ (337)
Investment gains/losses	492	125	997	19
Insurance and Other [Member]
Gain (Loss) on Investments [Line Items]
Investment gains/losses	455	102	889	(5)
Finance and Financial Products [Member]
Gain (Loss) on Investments [Line Items]
Investment gains/losses	37	23	108	24
Fixed Maturities [Member]
Gain (Loss) on Investments [Line Items]
Gross gains from sales and other disposals	67	58	82	91
Gross losses from sales and other disposals	(38)	(329)	(92)	(345)
Equity Securities [Member]
Gain (Loss) on Investments [Line Items]
Gross gains from sales and other disposals	261	385	370	573
Gross losses from sales and other disposals	(19)	(7)	(20)	(7)
Other Types of Investments [Member]
Gain (Loss) on Investments [Line Items]
Investment gains/losses	$ 221	$ 18	$ 742	$ 44