Charges and Credits (Details) (USD $) In Millions	3 Months Ended				9 Months Ended
	Sep. 30, 2011	Jun. 30, 2011	Mar. 31, 2011	Mar. 31, 2010	Sep. 30, 2011	Sep. 30, 2010
Restructuring Charges [Abstract]
Charges Pretax					$ 143
Charges, tax					27
Charges					116
Medicare Part D Subsidy [Member]
Restructuring Charges [Abstract]
Charges, tax						(40)
Charges				40		40
Merger and integration-related transaction costs
Restructuring Charges [Abstract]
Charges Pretax	27	32	34	35	93	56
Charges, tax					17
Charges	23	24	28		76	55
Donation to Schlumberger Foundation [Member]
Restructuring Charges [Abstract]
Charges Pretax					50
Charges, tax					10
Charges					$ 40