Earnings Per Share (Computation Of Basic And Diluted Income Per Common Share From Continuing Operations) (Details) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2012	Jun. 30, 2011	Jun. 30, 2012	Jun. 30, 2011
Earnings Per Share [Abstract]
Income (loss) from continuing operations attributable to OM Group, Inc. common stockholders	$ (22,513)	$ 24,709	$ (10,428)	$ 55,601
Weighted average shares outstanding - basic (in shares)	31,882	30,535	31,878	30,531
Dilutive effect of stock options and restricted stock (in shares)	0	186	0	177
Weighted average shares outstanding - assuming dilution (in shares)	31,882	30,721	31,878	30,708
Earnings per common share:
Income (loss) from continuing operations attributable to OM Group, Inc. common stockholders - basic (in dollars per share)	$ (0.71)	$ 0.81	$ (0.33)	$ 1.82
Income (loss) from continuing operations attributable to OM Group, Inc. common stockholders - assuming dilution (in dollars per share)	$ (0.71)	$ 0.80	$ (0.33)	$ 1.81