Components of Total Equity and Comprehensive Income (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Feb. 28, 2014	Feb. 28, 2013	Feb. 28, 2014	Feb. 28, 2013
Stockholders Equity Note [Line Items]
Total equity, beginning of period	$ 1,493,860	$ 1,392,542	$ 1,354,933	$ 1,313,983
Net Income (Loss)	16,911	(42,192)	192,214	41,762
Other Comprehensive (Loss) Income:
Foreign currency translation adjustments	(12,146)	(19,938)	(1,355)	17,256
Pension and other postretirement benefit liability adjustments, net of tax	3,826	5,278	8,961	9,862
Unrealized (loss) gain on securities, net of tax	(2,314)	(712)	2,648	1,012
Unrealized gain (loss) on derivatives, net of tax	(484)	328	(1,369)	(229)
Total Other Comprehensive (Loss) Income	(11,118)	(15,044)	8,885	27,901
Total Comprehensive Income	5,793	(57,236)	201,099	69,663
Dividends paid	(31,967)	(29,778)	(93,763)	(87,832)
Other noncontrolling interest activity		(152)		157
Shares repurchased	(28)	(1,235)	(6,895)	(2,329)
Stock option exercises, net	(1,640)	1,384	1,022	3,749
Stock based compensation expense	682	583	2,164	1,794
Restricted awards, net	5,237	3,637	13,377	10,560
Convertible bond, equity component, net of tax	13,470		13,470
Deferred financing costs, convertible bond	(492)		(492)
Total Equity, end of period	1,484,915	1,309,745	1,484,915	1,309,745
Total RPM International Inc. Equity
Stockholders Equity Note [Line Items]
Total equity, beginning of period	1,322,222	1,242,952	1,200,858	1,183,656
Net Income (Loss)	16,221	(42,356)	182,881	33,225
Other Comprehensive (Loss) Income:
Foreign currency translation adjustments	(18,446)	(19,401)	(16,108)	5,604
Pension and other postretirement benefit liability adjustments, net of tax	3,469	4,736	8,430	9,512
Unrealized (loss) gain on securities, net of tax	(2,312)	(1,626)	2,597	1,064
Unrealized gain (loss) on derivatives, net of tax	(380)	238	(1,076)	(178)
Total Other Comprehensive (Loss) Income	(17,669)	(16,053)	(6,157)	16,002
Total Comprehensive Income	(1,448)	(58,409)	176,724	49,227
Dividends paid	(31,967)	(29,778)	(93,763)	(87,832)
Other noncontrolling interest activity	(832)	(152)	(1,261)	157
Shares repurchased	(28)	(1,235)	(6,895)	(2,329)
Stock option exercises, net	(1,640)	1,384	1,022	3,749
Stock based compensation expense	682	583	2,164	1,794
Restricted awards, net	5,237	3,637	13,377	10,560
Convertible bond, equity component, net of tax	13,470		13,470
Deferred financing costs, convertible bond	(492)		(492)
Total Equity, end of period	1,305,204	1,158,982	1,305,204	1,158,982
Noncontrolling Interest
Stockholders Equity Note [Line Items]
Total equity, beginning of period	171,638	149,590	154,075	130,327
Net Income (Loss)	690	164	9,333	8,537
Other Comprehensive (Loss) Income:
Foreign currency translation adjustments	6,300	(537)	14,753	11,652
Pension and other postretirement benefit liability adjustments, net of tax	357	542	531	350
Unrealized (loss) gain on securities, net of tax	(2)	914	51	(52)
Unrealized gain (loss) on derivatives, net of tax	(104)	90	(293)	(51)
Total Other Comprehensive (Loss) Income	6,551	1,009	15,042	11,899
Total Comprehensive Income	7,241	1,173	24,375	20,436
Other noncontrolling interest activity	832		1,261
Total Equity, end of period	$ 179,711	$ 150,763	$ 179,711	$ 150,763