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, 2013		Nov. 30, 2012		Nov. 30, 2013		Nov. 30, 2012
Numerator for earnings per share:
Net income attributable to RPM International Inc. stockholders	$ 63,562		$ 41,668		$ 166,660		$ 75,581
Less: Allocation of earnings and dividends to participating securities	(1,379)		(929)		(3,521)		(1,526)
Net income available to common shareholders - basic	62,183		40,739		163,139		74,055
Add: Undistributed earnings reallocated to unvested shareholders	6		2		17		2
Net income available to common shareholders - diluted	$ 62,189		$ 40,741		$ 163,156		$ 74,057
Denominator for basic and diluted earnings per share:
Basic weighted average common shares	129,426		128,885		129,385		128,844
Average diluted options	992		815		974		791
Net issuable common share equivalents
Total shares for diluted earnings per share	130,418	[1],[2]	129,700	[1],[2]	130,359	[1],[2]	129,635	[1],[2]
Earnings per Share of Common Stock Attributable to RPM International Inc. Stockholders:
Basic Earnings Per Share of Common Stock	$ 0.48		$ 0.32		$ 1.26		$ 0.57
Diluted Earnings Per Share of Common Stock	$ 0.48		$ 0.31		$ 1.25		$ 0.57

[1] For the quarters ended November 30, 2013 and 2012, respectively, approximately 3,078,000 shares and 3,151,000 shares of stock granted under stock-based compensation plans were excluded from the calculation of diluted EPS, as the effect would have been anti-dilutive.

[2] For the six month periods ended November 30, 2013 and 2012, approximately 2,939,000 shares and 2,970,000 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.