Previously Reported and Restated Balances of Affected Line Items in Financial Statements (Detail) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended
	Aug. 31, 2012		Aug. 31, 2011		May 31, 2012		May 31, 2011
Consolidated Balance Sheet
Deferred income taxes	$ 24,253	[1]			$ 18,752
Other accrued liabilities	195,743	[1]			144,911
Retained earnings	685,201	[1]			686,818
Total RPM International Inc. stockholders' equity	1,218,992	[1]			1,183,656
Total equity	1,362,352	[1]	1,435,737		1,313,983	[1]	1,387,368
Consolidated Statements of Income
Estimated Loss Contingency	11,418	[1]
Income before income taxes	60,644	[1]	118,704
Provision for Income Taxes	30,025	[1]	35,364
Net income	30,619	[1]	83,340
Net income attributable to RPM International Inc. Stockholders	26,665	[1]	76,811
Earnings Per Share-Basic	$ 0.20	[1]	$ 0.59
Earnings Per Share-Diluted	$ 0.20	[1],[2]	$ 0.59	[2]
Consolidated Statements of Comprehensive Income
Net income	30,619	[1]	83,340
Total Comprehensive Income	70,890	[1]	72,122
Comprehensive Income Attributable to RPM International Inc. Stockholders	57,857	[1]	64,928
Consolidated Statement of Cash Flows
Net income	30,619	[1]	83,340
Estimated Loss Contingency	11,418	[1]
Deferred income taxes	(2,296)	[1]	(1,374)
Cash From Operating Activities	17,734	[1]	7,476
As Reported
Consolidated Balance Sheet
Deferred income taxes	20,083
Other accrued liabilities	184,325
Retained earnings	692,449
Total RPM International Inc. stockholders' equity	1,226,240
Total equity	1,369,600
Consolidated Statements of Income
Income before income taxes	72,062
Provision for Income Taxes	34,195
Net income	37,867
Net income attributable to RPM International Inc. Stockholders	33,913
Earnings Per Share-Basic	$ 0.26
Earnings Per Share-Diluted	$ 0.26
Consolidated Statements of Comprehensive Income
Net income	37,867
Total Comprehensive Income	78,138
Comprehensive Income Attributable to RPM International Inc. Stockholders	65,105
Consolidated Statement of Cash Flows
Net income	37,867
Deferred income taxes	1,874
Cash From Operating Activities	17,734
Adjustments
Consolidated Balance Sheet
Deferred income taxes	4,170
Other accrued liabilities	11,418
Retained earnings	(7,248)
Total RPM International Inc. stockholders' equity	(7,248)
Total equity	(7,248)
Consolidated Statements of Income
Estimated Loss Contingency	11,418
Income before income taxes	(11,418)
Provision for Income Taxes	(4,170)
Net income	(7,248)
Net income attributable to RPM International Inc. Stockholders	(7,248)
Earnings Per Share-Basic	$ (0.06)
Earnings Per Share-Diluted	$ (0.06)
Consolidated Statements of Comprehensive Income
Net income	(7,248)
Total Comprehensive Income	(7,248)
Comprehensive Income Attributable to RPM International Inc. Stockholders	(7,248)
Consolidated Statement of Cash Flows
Net income	(7,248)
Estimated Loss Contingency	11,418
Deferred income taxes	$ (4,170)

[1] Restated

[2] For the quarters ended August 31, 2012 and 2011, approximately 2,954,000 and 2,750,000 shares of stock, respectively, granted under stock-based compensation plans were excluded from the calculation of diluted earnings per share, as the effect would have been anti-dilutive.