Summary of Accounting Policies - Reconciliation of Earnings Per Share (Detail) (USD $) In Millions, except Per Share data, unless otherwise specified	12 Months Ended
Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Earnings Per Share [Line Items]
Schlumberger Income from Continuing Operations, Basic	$ 7,191	$ 6,239	$ 5,132
Weighted Average Shares Outstanding, Basic	1,330	1,349	1,250
Schlumberger Income from Continuing Operations, Assumed conversion of debentures			3
Weighted Average Shares Outstanding, Assumed conversion of debentures			2
Schlumberger Income from Continuing Operations, Assumed exercise of stock options	5	10	9
Schlumberger Income from Continuing Operations, Unvested restricted stock	4	2	2
Schlumberger Income from Continuing Operations, Diluted	$ 5,439	$ 4,720	$ 4,258
Weighted Average Shares Outstanding, Diluted	1,339	1,361	1,263
Basic	$ 4.09	$ 3.50	$ 3.40
Diluted	$ 4.06	$ 3.47	$ 3.37

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Includes adjustments resulting from the assumption that dilutive convertible securities were converted, options or warrants were exercised, or that other shares were issued upon the satisfaction of certain conditions.

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This element represents the income or loss from continuing operations attributable to the economic entity which may also be defined as revenue less expenses from ongoing operations, after income or loss from equity method investments, but before income taxes, extraordinary items, and noncontrolling interest.

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The amount of net income (loss) from continuing operations per each share of common stock or unit outstanding during the reporting period.

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Nonvested equity-based payment awards that contain forfeitable rights to dividends or dividend equivalents (whether paid or unpaid) that result in incremental common shares.

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Net Income or Loss Available to Common Stockholders plus adjustments resulting from the assumption that dilutive convertible securities were converted, options or warrants were exercised, or that other shares were issued upon the satisfaction of certain conditions.

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The average number of shares or units issued and outstanding that are used in calculating diluted EPS or earnings per unit (EPU), determined based on the timing of issuance of shares or units in the period.

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