Consolidated Statements of Equity - USD ($) $ in Thousands	Total	DHybrid Systems LLC	Worthington Specialty Processing	Common Shares	Additional Paid-in Capital	Additional Paid-in Capital DHybrid Systems LLC	Accumulated Other Comprehensive Loss, Net of Tax	Retained Earnings	Total	Total DHybrid Systems LLC	Noncontrolling Interests	Noncontrolling Interests DHybrid Systems LLC	Noncontrolling Interests Worthington Specialty Processing
Balance at May. 31, 2014	$ 944,882				$ 262,610		$ (3,581)	$ 591,783	$ 850,812		$ 94,070
Balance (in shares) at May. 31, 2014				67,408,484
Net earnings	87,256							76,785	76,785		10,471
Other comprehensive income (loss)	(49,620)						(47,123)		(47,123)		(2,497)
Acquisition		$ 4,082										$ 4,082
Common shares issued, net of withholding tax	2,910				2,910				2,910
Common shares issued, net of withholding tax (in shares)				909,181
Theoretical common shares in NQ plans	14,560				14,560				14,560
Stock-based compensation	26,837				26,837				26,837
Purchases and retirement of common shares	$ (127,360)				(17,839)			(109,521)	(127,360)
Purchases and retirement of common shares (in shares)	(4,176,187)			(4,176,187)
Dividends to noncontrolling interests	$ (15,189)										(15,189)
Cash dividends declared ($0.72 per share in 2015, $0.76 per share in 2016 and $0.80 per share in 2017)	(48,309)							(48,309)	(48,309)
Balance at May. 31, 2015	840,049				289,078		(50,704)	510,738	749,112		90,937
Balance (in shares) at May. 31, 2015				64,141,478
Net earnings	157,628							143,715	143,715		13,913
Other comprehensive income (loss)	24,866						22,139		22,139		2,727
Acquisition			$ 28,004										$ 28,004
Common shares issued, net of withholding tax	8,707				8,707				8,707
Common shares issued, net of withholding tax (in shares)				892,190
Theoretical common shares in NQ plans	960				960				960
Stock-based compensation	16,534				16,534				16,534
Purchases and retirement of common shares	$ (99,847)				(16,295)			(83,552)	(99,847)
Purchases and retirement of common shares (in shares)	(3,500,000)			(3,500,000)
Dividends to noncontrolling interests	$ (9,106)										(9,106)
Cash dividends declared ($0.72 per share in 2015, $0.76 per share in 2016 and $0.80 per share in 2017)	(47,949)							(47,949)	(47,949)
Balance at May. 31, 2016	919,846				298,984		(28,565)	522,952	793,371		126,475
Balance (in shares) at May. 31, 2016				61,533,668
Net earnings	217,937							204,515	204,515		13,422
Other comprehensive income (loss)	762						790		790		(28)
Common shares issued, net of withholding tax	(9,075)				(9,075)				(9,075)
Common shares issued, net of withholding tax (in shares)				1,268,788
Theoretical common shares in NQ plans	1,259				1,259				1,259
Stock-based compensation	$ 13,158				13,158				13,158
Purchase of noncontrolling interest		$ (2,888)			(935)	$ (935)				$ (935)		$ (1,953)
Purchases and retirement of common shares (in shares)	0
Dividends to noncontrolling interests	$ (15,622)										(15,622)
Cash dividends declared ($0.72 per share in 2015, $0.76 per share in 2016 and $0.80 per share in 2017)	(51,448)							(51,448)	(51,448)
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