Pension and Other Postretirement Benefits (Details 1) (Postretirement Medical Plan [Member], USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2012	Mar. 31, 2011
Postretirement Medical Plan [Member]
Net periodic benefit cost for the Schlumberger US postretirement medical plan
Service cost-benefits earned during the period	$ 7	$ 7
Interest cost on accumulated postretirement benefit obligation	15	14
Expected return on plan assets	(7)	(5)
Amortization of prior service cost	(2)	(3)
Amortization of net loss	5	3
Total pension cost	$ 18	$ 16