Components of Total Equity and Comprehensive Income (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Aug. 31, 2013	Aug. 31, 2012
Stockholders Equity Note [Line Items]
Total equity, beginning of period	$ 1,354,933	$ 1,313,983
Net income	106,889	37,867
Other Comprehensive Income:
Foreign currency translation adjustments	(13,414)	39,230
Pension and other postretirement benefit liability adjustments, net of tax	2,924	1,206
Unrealized (loss) on securities, net of tax	(1,439)	(352)
Unrealized gain (loss) on derivatives, net of tax	109	187
Total Other Comprehensive (Loss) Income	(11,820)	40,271
Total Comprehensive Income	95,069	78,138
Dividends paid	(29,836)	(28,281)
Other noncontrolling interest activity		1,284
Stock option exercises, net	2,401	603
Stock based compensation expense	709	588
Restricted awards, net	451	3,285
Total Equity, end of period	1,423,727	1,369,600
Total RPM International Inc. Equity
Stockholders Equity Note [Line Items]
Total equity, beginning of period	1,200,858	1,183,656
Net income	103,098	33,913
Other Comprehensive Income:
Foreign currency translation adjustments	(17,071)	28,664
Pension and other postretirement benefit liability adjustments, net of tax	2,761	1,534
Unrealized (loss) on securities, net of tax	(1,432)	825
Unrealized gain (loss) on derivatives, net of tax	86	169
Total Other Comprehensive (Loss) Income	(15,656)	31,192
Total Comprehensive Income	87,442	65,105
Dividends paid	(29,836)	(28,281)
Other noncontrolling interest activity	(341)	1,284
Stock option exercises, net	2,401	603
Stock based compensation expense	709	588
Restricted awards, net	451	3,285
Total Equity, end of period	1,261,684	1,226,240
Noncontrolling Interest
Stockholders Equity Note [Line Items]
Total equity, beginning of period	154,075	130,327
Net income	3,791	3,954
Other Comprehensive Income:
Foreign currency translation adjustments	3,657	10,566
Pension and other postretirement benefit liability adjustments, net of tax	163	(328)
Unrealized (loss) on securities, net of tax	(7)	(1,177)
Unrealized gain (loss) on derivatives, net of tax	23	18
Total Other Comprehensive (Loss) Income	3,836	9,079
Total Comprehensive Income	7,627	13,033
Other noncontrolling interest activity	341
Total Equity, end of period	$ 162,043	$ 143,360