Schedule of Consideration Transferred and Fair Value Assigned to Assets Acquired And Liabilities Assumed (Detail) - USD ($) $ in Thousands	12 Months Ended
	May 31, 2016	May 31, 2017	May 31, 2015
Estimated Fair Value of Assets Acquired and Liabilities Assumed:
Goodwill	$ 246,067	$ 247,673	$ 238,999
Worthington Specialty Processing
Estimated Fair Value of Assets Acquired and Liabilities Assumed:
Cash	6,902
Accounts receivable	10,233
Inventories	3,349
Prepaid expense and other	809
Intangible assets	5,200
Other assets	2,608
Property, plant and equipment	38,657
Total identifiable assets	67,758
Accounts payable	(6,963)
Accrued liabilities	(1,728)
Net assets	59,067
Goodwill	1,312
Total cash consideration	60,379
Noncontrolling interest	(28,004)
Total consideration, less noncontrolling interest	32,375
CryoScience
Estimated Fair Value of Assets Acquired and Liabilities Assumed:
Accounts receivable	2,367
Inventories	5,762
Prepaid expense and other	208
Intangible assets	5,260
Property, plant and equipment	13,400
Total identifiable assets	26,997
Accounts payable	(2,808)
Other accrued items	(318)
Net assets	23,871
Goodwill	6,713
Purchase price	30,584
Plus: estimated working capital deficit	772
Cash paid at closing	$ 31,356