Summary Of Major Accounting Policies - Acquisitions (Details) (USD $) In Millions, unless otherwise specified	Dec. 31, 2011 Norse Cutting and Abandonment AS [Member]	Dec. 31, 2011 AGR Field Operations [Member]	Dec. 31, 2011 Mechanica AS [Member]	Mar. 31, 2012 Metacor Holdings Ltd [Member]
Business Acquisition [Line Items]
Business Acquisition, Cost of Acquired Entity, Purchase Price	$ 50		$ 17	$ 9
Business Combination, Separately Recognized Transactions, Additional Disclosures, Acquisition Costs		220
Business Acquisition, Purchase Price Allocation, Goodwill Amount		165	9
Business Acquisition, Purchase Price Allocation, Intangible Assets Not Amortizable		$ 32	$ 5