Consolidated Statements of Comprehensive Income - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Nov. 30, 2020	Nov. 30, 2019	Nov. 30, 2020	Nov. 30, 2019
Statement Of Income And Comprehensive Income [Abstract]
Net Income	$ 127,884	$ 77,322	$ 308,670	$ 183,818
Other comprehensive income (loss), net of tax:
Foreign currency translation adjustments (net of tax of $81; $0 $2,944 and $0, respectively)	12,495	20,967	77,162	(7,467)
Pension and other postretirement benefit liability adjustments (net of tax of $1,722; $1,015; $2,508 and $2,119, respectively)	5,644	3,404	8,904	7,027
Unrealized gain (loss) on securities and other (net of tax of $240; $0; $322 and $1, respectively)	80	(155)	170	216
Unrealized gain (loss) on derivatives (net of tax of $119; $305; $5,662 and $274, respectively)	(376)	381	(18,489)	1,165
Total other comprehensive income	17,843	24,597	67,747	941
Total Comprehensive Income	145,727	101,919	376,417	184,759
Less: Comprehensive Income Attributable to Noncontrolling Interests	225	343	484	620
Comprehensive Income Attributable to RPM International Inc. Stockholders	$ 145,502	$ 101,576	$ 375,933	$ 184,139