Risk Management (Schedule Of Largest Notional Amounts Of The Positions To Buy Or Sell Foreign Currency) (Details) (USD $) In Millions, unless otherwise specified	Dec. 31, 2012	Dec. 31, 2011
Foreign Currency Contracts
Notional amount of foreign currency derivatives	$ 523	$ 524
British Pound
Foreign Currency Contracts
Notional amount of foreign currency derivatives	225	55
Chinese Renminbi
Foreign Currency Contracts
Notional amount of foreign currency derivatives	(99)	(283)
Norwegian Krone
Foreign Currency Contracts
Notional amount of foreign currency derivatives	(48)	0
Israeli Shekel
Foreign Currency Contracts
Notional amount of foreign currency derivatives	(35)	8
Japanese Yen
Foreign Currency Contracts
Notional amount of foreign currency derivatives	$ 32	$ 46