Charges (Details) (USD $) In Millions	3 Months Ended			6 Months Ended
	Jun. 30, 2011	Mar. 31, 2011	Mar. 31, 2010	Jun. 30, 2011	Jun. 30, 2010
Summary of Charges
Charges, pretax	$ 82	$ 34		$ 116	$ 35
Charges, tax				24	(40)
Charges, net of tax				92	75
Medicare Part D Subsidy [Member]
Summary of Charges
Charges, tax					(40)
Charges, net of tax			40		40
Merger Related Transaction Costs [Member]
Summary of Charges
Charges, pretax	32	34	35	66	35
Charges, tax				14
Charges, net of tax	24	28		52	35
Donation to Schlumberger Foundation [Member]
Summary of Charges
Charges, pretax				50
Charges, tax				10
Charges, net of tax				40
General and administrative [Member]
Summary of Charges
Charges, pretax	50
Charges, net of tax	$ 40