Deferred Policy Acquisition Costs (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Deferred policy acquisition costs and the related amortization [Abstract]
Balance, beginning of year	$ 1,562	$ 1,533	$ 1,532
Costs deferred during year [Abstract]
Commissions and brokerage	1,910	1,734	1,663
Premium taxes and assessments	242	242	240
Salaries and operating costs	1,136	1,121	1,091
Total costs deferred during year	3,288	3,097	2,994
Foreign currency translation effect	5	(1)	28
Amortization during year	(3,225)	(3,067)	(3,021)
Balance, end of year	$ 1,630	$ 1,562	$ 1,533