Earnings Per Share (Computation of Income per Common Share from Continuing Operations) (Details) (USD $) In Thousands, except Per Share data	3 Months Ended	6 Months Ended
Jun. 30, 2011	Jun. 30, 2010	Jun. 30, 2011	Jun. 30, 2010
Earnings Per Share
Income from continuing operations attributable to OM Group, Inc. common stockholders	$ 24,709	$ 13,307	$ 55,601	$ 35,770
Weighted average shares outstanding - basic	30,535	30,471	30,531	30,388
Dilutive effect of stock options and restricted stock	186	120	177	134
Weighted average shares outstanding - assuming dilution	30,721	30,591	30,708	30,522
Income from continuing operations attributable to OM Group, Inc. common stockholders - basic	$ 0.81	$ 0.44	$ 1.82	$ 1.18
Income from continuing operations attributable to OM Group, Inc. common stockholders - assuming dilution	$ 0.80	$ 0.43	$ 1.81	$ 1.17

This element represents the income or loss from continuing operations attributable to the parent which may also be defined as revenue less expenses and taxes from ongoing operations before extraordinary items but after deduction of those portions of income or loss from continuing operations that are allocable to noncontrolling interests, if any.

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+ Details

- Definition

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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- Definition

The amount of net income (loss) derived from continuing operations during the period available to each share of common stock or common unit outstanding during the reporting period and to each share or unit that would have been outstanding assuming the issuance of common shares or units for all dilutive potential common shares or units outstanding during the reporting period.

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+ Details

- Definition

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.

+ References+ Details

- Definition

Number of [basic] shares or units, after adjustment for contingently issuable shares or units and other shares or units not deemed outstanding, determined by relating the portion of time within a reporting period that common shares or units have been outstanding to the total time in that period.

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