Pension and Other Postretirement Benefits (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2012	Mar. 31, 2011
US [Member]
Net Pension Cost for the Schlumberger Pension Plans
Service cost-benefits earned during the period	$ 17	$ 16
Interest cost on projected benefit obligation	38	38
Expected return on plan assets	(46)	(43)
Amortization of prior service cost	3	3
Amortization of net loss	23	22
Total pension cost	35	36
International [Member]
Net Pension Cost for the Schlumberger Pension Plans
Service cost-benefits earned during the period	21	17
Interest cost on projected benefit obligation	58	56
Expected return on plan assets	(80)	(70)
Amortization of prior service cost	30	31
Amortization of net loss	15	8
Total pension cost	$ 44	$ 42