Income Taxes - Earnings before Income Taxes (Detail) - USD ($) $ in Thousands		12 Months Ended
		May 31, 2021	May 31, 2020	May 31, 2019
Income Tax Disclosure [Abstract]
U.S. based operations		$ 897,601	$ 99,493	$ 173,200
Non – U.S. based operations		20,116	11,293	33,256
Earnings before income taxes		917,717	110,786	206,456
Net earnings attributable to noncontrolling interests	[1]	17,655	5,648	9,818
Earnings before income taxes attributable to controlling interest		$ 900,062	$ 105,138	$ 196,638

[1] Net earnings attributable to noncontrolling interests are not taxable to Worthington.