Income Taxes - Earnings before Income Taxes (Detail) - USD ($) $ in Thousands		12 Months Ended
		May 31, 2020	May 31, 2019	May 31, 2018
Income Tax Disclosure [Abstract]
U.S. based operations		$ 99,493	$ 173,200	$ 177,088
Non – U.S. based operations		11,293	33,256	31,982
Earnings before income taxes		110,786	206,456	209,070
Net earnings attributable to noncontrolling interests	[1]	5,648	9,818	6,056
Earnings before income taxes attributable to controlling interest		$ 105,138	$ 196,638	$ 203,014

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