Consolidated Statements of Comprehensive Income - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Feb. 28, 2019	Feb. 28, 2018	Feb. 28, 2019	Feb. 28, 2018
Statement Of Income And Comprehensive Income [Abstract]
Net Income	$ 14,496	$ 40,588	$ 133,855	$ 253,349
Other comprehensive income (loss), net of tax:
Foreign currency translation adjustments	20,823	31,133	(32,111)	67,453
Pension and other postretirement benefit liability adjustments (net of tax of $711; $1,319; $2,801 and $3,576, respectively)	2,479	2,279	8,962	5,974
Unrealized gain (loss) on securities and other (net of tax of $0; $(1,070); $543 and $43, respectively)	221	(2,380)	1,183	91
Unrealized (loss) gain on derivatives	(604)	(2,137)	2,667	(5,277)
Total other comprehensive income (loss)	22,919	28,895	(19,299)	68,241
Total Comprehensive Income	37,415	69,483	114,556	321,590
Less: Comprehensive (Loss) Income Attributable to Noncontrolling Interests	(219)	393	(14)	1,234
Comprehensive Income Attributable to RPM International Inc. Stockholders	$ 37,634	$ 69,090	$ 114,570	$ 320,356