Financial Instruments (Details 3) (USD $) In Millions, unless otherwise specified	Dec. 31, 2011
Australia, Dollars
Summarization for foreign currency forward purchase and sale contracts
Notional Amount in Foreign Currency, Purchase	$ 2
United Kingdom, Pounds
Summarization for foreign currency forward purchase and sale contracts
Notional Amount in Foreign Currency, Purchase	4
Euro Member Countries, Euro
Summarization for foreign currency forward purchase and sale contracts
Notional Amount in Foreign Currency, Sell	(56)
Japan, Yen
Summarization for foreign currency forward purchase and sale contracts
Notional Amount in Foreign Currency, Purchase	431
South Africa, Rand
Summarization for foreign currency forward purchase and sale contracts
Notional Amount in Foreign Currency, Purchase	92
United States of America, Dollars
Summarization for foreign currency forward purchase and sale contracts
Notional Amount in Foreign Currency, Purchase	2
Notional Amount in Foreign Currency, Sell	(47)
Other Currency [Member]
Summarization for foreign currency forward purchase and sale contracts
Notional Amount in Foreign Currency, Purchase	1
Notional Amount in Foreign Currency, Sell	$ (1)