Pension and Other Postretirement Benefits (Details) (USD $) In Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2011	Jun. 30, 2010	Jun. 30, 2011	Jun. 30, 2010
United States Pension Plans of US Entity Defined Benefit
Net Pension Cost for the Schlumberger Pension Plans
Service cost-benefits earned during period	$ 14	$ 13	$ 30	$ 28
Interest cost on projected benefit obligation	37	35	75	71
Expected return on plan assets	(42)	(47)	(85)	(95)
Amortization of prior service cost	3	1	6	2
Amortization of net loss	22	15	44	31
Total pension cost	34	17	70	37
Foreign Pension Plans, Defined Benefit
Net Pension Cost for the Schlumberger Pension Plans
Service cost-benefits earned during period	17	10	34	24
Interest cost on projected benefit obligation	57	51	113	103
Expected return on plan assets	(71)	(57)	(141)	(115)
Amortization of prior service cost	30	29	61	57
Amortization of net loss	8	5	16	10
Total pension cost	$ 41	$ 38	$ 83	$ 79