Schedule V. Valuation and Qualifying Accounts (Schedule of valuation and qualifying accounts) (Details) (Allowance for doubtful accounts, insurance and reinsurance receivables [Member], USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2011		Dec. 31, 2010		Dec. 31, 2009
Allowance for doubtful accounts, insurance and reinsurance receivables [Member]
Movement in valuation allowances and reserves [Roll Forward]
Balance at beginning of period	$ 285		$ 553		$ 587
Charged to costs and expenses	(55)		(232)		4
Charged to other accounts		[1]	(1)	[1]	(1)	[1]
Deductions	(27)		(35)		(37)
Balance at end of period	$ 203		$ 285		$ 553

[1] Amount includes effects of foreign currency translation.