Asset Acquisitions, Dispositions and Other Transactions (Details 4) (Libya activity, USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2010	Jun. 30, 2011	Mar. 31, 2011
Libya activity
Asset acquisitions, dispositions and other transactions
Capitalized and suspended exploration costs written off			$ 35
Net book value of Libyan producing properties		847
Proved reserves, net (in barrels)	57,000,000
Net proved reserves as a percentage of total proved reserves (as a percent)	2.00%
Sales and production volumes (BOE per day)	13,000
Sales and production volumes as a percentage of worldwide sales and production volumes (as a percent)	2.00%
After-tax income from Libyan operations, excluding exploration costs	25
After-tax cashflows from Libyan operations, excluding exploration costs	$ 31