Supplementary Balance Sheet Data (Details) (USD $) In Millions, unless otherwise specified	Sep. 30, 2012	Dec. 31, 2011	Sep. 30, 2011
Supplementary Balance Sheet Data
Accounts receivable - allowance for doubtful accounts	$ 64	$ 55	$ 64
Accounts receivable - allowance for sales returns	193	187	233
Prepublication costs - accumulated amortization	1,200	1,066	1,038
Property and equipment - accumulated depreciation	$ 1,021	$ 1,066	$ 1,057