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			6 Months Ended
	Nov. 30, 2012		Nov. 30, 2011	Nov. 30, 2012		Nov. 30, 2011	Aug. 31, 2012		May 31, 2012		Aug. 31, 2011	May 31, 2011
Consolidated Statement of Cash Flows
Net income	$ 35,343	[1]	$ 53,919	$ 65,962	[1]	$ 137,259
Estimated loss contingency	16,926	[1]		28,344	[1]
Deferred income taxes				(6,379)	[1]	(1,620)
Cash from Operating Activities				127,621	[1]	110,030
Consolidated Balance Sheets
Deferred income taxes	31,393	[1]		31,393	[1]				18,752
Other accrued liabilities	220,704	[1]		220,704	[1]				144,911
Retained earnings	686,353	[1]		686,353	[1]				686,818
Total RPM International Inc. stockholders' equity	1,224,960	[1]		1,224,960	[1]				1,183,656
Total equity	1,374,550	[1]	1,388,027	1,374,550	[1]	1,388,027	1,362,352	[1]	1,313,983	[1]	1,435,737	1,387,368
Consolidated Statements of Income
Estimated loss contingency	16,926	[1]		28,344	[1]
Income before income taxes	54,116	[1]	76,170	114,760	[1]	194,874
Provision for Income Taxes	18,773	[1]	22,251	48,798	[1]	57,615
Net income	35,343	[1]	53,919	65,962	[1]	137,259
Net income attributable to RPM International Inc. stockholders	30,924	[1]	49,931	57,589	[1]	126,742
Earnings Per Share - Basic	$ 0.23	[1]	$ 0.38	$ 0.44	[1]	$ 0.97
Earnings Per Share - Diluted	$ 0.23	[1]	$ 0.38	$ 0.44	[1]	$ 0.97
Consolidated Statements of Comprehensive Income
Net income	35,343	[1]	53,919	65,962	[1]	137,259
Total Comprehensive Income	38,017	[1]	(17,725)	108,907	[1]	54,397
Comprehensive Income Attributable to RPM International Inc. Stockholders	31,787	[1]	(19,260)	89,644	[1]	45,668
As Reported
Consolidated Statement of Cash Flows
Net income	46,087			83,954
Deferred income taxes				3,973
Cash from Operating Activities				127,621
Consolidated Balance Sheets
Deferred income taxes	21,041			21,041
Other accrued liabilities	192,360			192,360
Retained earnings	704,345			704,345
Total RPM International Inc. stockholders' equity	1,242,952			1,242,952
Total equity	1,392,542			1,392,542
Consolidated Statements of Income
Income before income taxes	71,042			143,104
Provision for Income Taxes	24,955			59,150
Net income	46,087			83,954
Net income attributable to RPM International Inc. stockholders	41,668			75,581
Earnings Per Share - Basic	$ 0.32			$ 0.57
Earnings Per Share - Diluted	$ 0.31			$ 0.57
Consolidated Statements of Comprehensive Income
Net income	46,087			83,954
Total Comprehensive Income	48,761			126,899
Comprehensive Income Attributable to RPM International Inc. Stockholders	42,531			107,636
Adjustments
Consolidated Statement of Cash Flows
Net income	(10,744)			(17,992)
Estimated loss contingency	16,926			28,344
Deferred income taxes				(10,352)
Consolidated Balance Sheets
Deferred income taxes	10,352			10,352
Other accrued liabilities	28,344			28,344
Retained earnings	(17,992)			(17,992)
Total RPM International Inc. stockholders' equity	(17,992)			(17,992)
Total equity	(17,992)			(17,992)
Consolidated Statements of Income
Estimated loss contingency	16,926			28,344
Income before income taxes	(16,926)			(28,344)
Provision for Income Taxes	(6,182)			(10,352)
Net income	(10,744)			(17,992)
Net income attributable to RPM International Inc. stockholders	(10,744)			(17,992)
Earnings Per Share - Basic	$ (0.09)			$ (0.13)
Earnings Per Share - Diluted	$ (0.08)			$ (0.13)
Consolidated Statements of Comprehensive Income
Net income	(10,744)			(17,992)
Total Comprehensive Income	(10,744)			(17,992)
Comprehensive Income Attributable to RPM International Inc. Stockholders	$ (10,744)			$ (17,992)

[1] Restated