Computation of Per Share Amounts (Detail) (USD $) In Millions, except Per Share data	3 Months Ended		6 Months Ended
	Jun. 30, 2011	Jun. 30, 2010	Jun. 30, 2011	Jun. 30, 2010
Numerator (in millions):
Net income attributable to The Lubrizol Corporation	$ 191.3	$ 201.4	$ 360.8	$ 363.7
Denominator (in millions of shares):
Weighted-average common shares outstanding	64.6	68.2	64.5	68.4
Dilutive effect of stock options and awards	1.5	1.6	1.5	1.4
Denominator for net income per share, diluted	66.1	69.8	66.0	69.8
Net income per share attributable to The Lubrizol Corporation, basic	$ 2.96	$ 2.95	$ 5.59	$ 5.32
Net income per share attributable to The Lubrizol Corporation, diluted	$ 2.90	$ 2.88	$ 5.47	$ 5.21