Consolidated Statements of Equity - USD ($) $ in Thousands	Total	Worthington Energy Innovations L L C	Worthington Samuel Coil Processing Llc	Common Shares	Additional Paid-in Capital	Accumulated Other Comprehensive Loss, Net of Tax	Retained Earnings	Total	Noncontrolling Interests	Noncontrolling Interests Worthington Energy Innovations L L C	Noncontrolling Interests Worthington Samuel Coil Processing Llc
Balance at May. 31, 2017	$ 1,073,929				$ 303,391	$ (27,775)	$ 676,019	$ 951,635	$ 122,294
Balance (in shares) at May. 31, 2017				62,802,456
Net earnings	200,850						194,794	194,794	6,056
Other comprehensive income (loss)	15,269					14,896		14,896	373
Common shares issued, net of withholding tax	(2,120)				(2,120)			(2,120)
Common shares issued, net of withholding tax (in shares)				449,465
Theoretical common shares in NQ plans	1,218				1,218			1,218
Stock-based compensation	13,460				13,460			13,460
Purchase of noncontrolling interest	(1,913)				924			924	(2,837)
Sale of controlling interest		$ (365)								$ (365)
Reclassification of stranded tax effects						(1,701)	1,701
Repurchases and retirement of common shares	$ (204,267)				(21,281)		(182,986)	(204,267)
Repurchases and retirement of common shares (in shares)	4,375,000			(4,375,000)
Dividends to noncontrolling interests	$ (7,915)								(7,915)
Cash dividends declared ($0.80 per share in 2017, $0.84 per share in 2018 and $0.92 per share in 2019)	(51,771)						(51,771)	(51,771)
Balance at May. 31, 2018	1,036,375				295,592	(14,580)	637,757	918,769	117,606
Balance (in shares) at May. 31, 2018				58,876,921
Net earnings	163,273						153,455	153,455	9,818
Other comprehensive income (loss)	(29,004)					(28,884)		(28,884)	(120)
Common shares issued, net of withholding tax	(6,371)				(6,371)			(6,371)
Common shares issued, net of withholding tax (in shares)				690,604
Theoretical common shares in NQ plans	680				680			680
Stock-based compensation	13,927				13,927			13,927
Repurchases and retirement of common shares	$ (168,113)				(20,651)		(147,462)	(168,113)
Repurchases and retirement of common shares (in shares)	4,100,000			(4,100,000)
ASC 606 transition adjustment	$ 1,744						1,174	1,174	570
Dividends to noncontrolling interests	(10,726)								(10,726)
Cash dividends declared ($0.80 per share in 2017, $0.84 per share in 2018 and $0.92 per share in 2019)	(53,391)						(53,391)	(53,391)
Balance at May. 31, 2019	948,394				283,177	(43,464)	591,533	831,246	117,148
Balance (in shares) at May. 31, 2019				55,467,525
Net earnings	84,444						78,796	78,796	5,648
Other comprehensive income (loss)	8,247					8,247		8,247
Common shares issued, net of withholding tax	(6,513)				(6,513)			(6,513)
Common shares issued, net of withholding tax (in shares)				448,960
Theoretical common shares in NQ plans	547				547			547
Stock-based compensation	13,191				13,191			13,191
Repurchases and retirement of common shares	$ (50,972)				(6,626)		(44,346)	(50,972)
Repurchases and retirement of common shares (in shares)	1,300,000			(1,300,000)
Consolidation of Worthington Samuel Coil Processing LLC			$ 24,269								$ 24,269
Dividends to noncontrolling interests	$ (1,453)								(1,453)
Cash dividends declared ($0.80 per share in 2017, $0.84 per share in 2018 and $0.92 per share in 2019)	(53,721)						(53,721)	(53,721)
Balance at May. 31, 2020	$ 966,433				$ 283,776	$ (35,217)	$ 572,262	$ 820,821	$ 145,612
Balance (in shares) at May. 31, 2020				54,616,485