Pension and Other Benefit Plans - Net Pension Cost for Schlumberger Pension Plans and US Postretirement Medical Plan (Detail) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
US Plan Assets [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost - benefits earned during the period	$ (68)	$ (59)
Interest cost on projected benefit obligation	(152)	(150)
International [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost - benefits earned during the period	(86)	(64)
Interest cost on projected benefit obligation	(241)	(226)
Postretirement medical plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost - benefits earned during the period	29	24	23
Interest cost on projected benefit obligation	58	57	58
Expected return on plan assets	(30)	(20)	(6)
Amortization of net loss	16	13	11
Amortization of prior service cost	(8)	(12)	(21)
Total pension cost	65	62	65
Net pension cost [Member] | US Plan Assets [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost - benefits earned during the period	68	59	56
Interest cost on projected benefit obligation	152	150	142
Expected return on plan assets	(185)	(170)	(191)
Amortization of net loss	93	90	60
Amortization of prior service cost	16	12	4
Total pension cost	144	141	71
Net pension cost [Member] | International [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost - benefits earned during the period	86	64	51
Interest cost on projected benefit obligation	241	226	208
Expected return on plan assets	(328)	(279)	(228)
Amortization of net loss	76	31	19
Amortization of prior service cost	120	120	113
Total pension cost	$ 195	$ 162	$ 163