Reconciliation of Numerator and Denominator of Basic and Diluted Earnings Per Share, Calculated using Two-Class Method (Detail) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended				6 Months Ended
	Nov. 30, 2012		Nov. 30, 2011		Nov. 30, 2012		Nov. 30, 2011
Numerator for earnings per share:
Net income attributable to RPM International Inc. stockholders	$ 30,924	[1]	$ 49,931		$ 57,589	[1]	$ 126,742
Less: Allocation of earnings and dividends to participating securities	(673)	[1]	(979)		(1,121)	[1]	(2,297)
Net income available to common shareholders - basic	30,251	[1]	48,952		56,468	[1]	124,445
Add: Undistributed earnings reallocated to unvested shareholders			2				5
Net income available to common shareholders - diluted	$ 30,251	[1]	$ 48,954		$ 56,468	[1]	$ 124,450
Denominator for basic and diluted earnings per share:
Basic weighted average common shares	128,885	[1]	127,986		128,844	[1]	128,048
Average diluted options	815	[1]	446		791	[1]	489
Net issuable common share equivalents		[1]				[1]
Total shares for diluted earnings per share	129,700	[1],[2],[3]	128,432	[2],[3]	129,635	[1],[2],[3]	128,537	[2],[3]
Earnings Per Share of Common Stock Attributable to RPM International Inc. Stockholders:
Basic Earnings Per Share of Common Stock	$ 0.23	[1]	$ 0.38		$ 0.44	[1]	$ 0.97
Diluted Earnings Per Share of Common Stock	$ 0.23	[1]	$ 0.38		$ 0.44	[1]	$ 0.97

[1] Restated

[2] For the quarters ended November 30, 2012 and 2011, approximately 3,151,000 shares and 2,722,000 shares of stock, respectively, granted under stock-based compensation plans were excluded from the calculation of diluted EPS for those periods, as the effect would have been anti-dilutive.

[3] For the six month periods ended November 30, 2012 and 2011, approximately 2,970,000 shares and 2,522,000 shares of stock, respectively, granted under stock-based compensation plans were excluded from the calculation of diluted EPS for those periods, as the effect would have been anti-dilutive.