Derivative Instruments and Hedging Activities (Details Textual) (USD $)	3 Months Ended
	Mar. 31, 2012 Country	Mar. 31, 2012 Designated as Hedging Instrument [Member] Debt [Member]	Mar. 31, 2012 Commodity Contracts [Member]	Sep. 30, 2009 3.00% Guaranteed Notes due 2013 [Member]	Sep. 30, 2009 3.00% Guaranteed Notes due 2013 [Member] Fixed Rate Debt [Member]	Sep. 30, 2009 3.00% Guaranteed Notes due 2013 [Member] Floating Rate Debt [Member]
Derivative Instruments and Hedging Activities (Textual) [Abstract]
Contracts outstanding in various foreign currencies relate to hedges of debt	$ 5,200,000,000	$ 3,900,000,000
Commodity forward contract outstanding			23,000,000
Notional amount of interest rate swap				450,000,000
Notes relating to interest rate swap				450,000,000
Derivative swap interest rate					3.00%	0.765%
Derivative Instruments and Hedging Activities (Additional Textual) [Abstract]
Number of countries in which Schlumberger conducts business	85
Recognized a cumulative net loss in Equity relating to revaluation of foreign currency forward contracts and foreign currency options designated as cash flow hedges	19,000,000
Contracts outstanding in various foreign currencies (US dollar equivalent)	5,200,000,000	3,900,000,000
Fixed rate debt aggregate, after taking into account the effects of the interest rate swaps	7,700,000,000
Variable rate debt aggregate, after taking into account the effects of the interest rate swaps	2,500,000,000
Short-term investments and Fixed income investments, held to maturity	$ 3,000,000,000