Income Taxes (Details) - USD ($) $ in Thousands	5 Months Ended	12 Months Ended
	May 31, 2018	May 31, 2020	May 31, 2019	May 31, 2018	May 31, 2017
Current:
U.S. federal statutory income tax rate (as a percent)	21.00%	21.00%	21.00%	29.20%	35.00%
Income tax benefit for the re-measurement impact				$ 14,100
Federal		$ 1,400	$ 4,800	14,600
State		900	100	100
Foreign		2,800	5,000	1,700
Total current		5,100	9,900	16,400
Deferred		500	(5,000)	(12,900)
Provision for income tax		5,600	4,900	3,500
Reasons for difference between the provision for income taxes on pre-tax income from the amount computed by applying the U.S. federal statutory tax rate
Provision for income tax at the federal statutory rate		6,400	18,700	22,500
Deferred tax re-measurement from the Tax Reform Act				(14,100)
Excess tax benefits from stock-based compensation		(2,100)	(2,700)	(2,900)
State income taxes, net of federal benefit and refunds		1,100	1,900	1,500
Change in valuation allowance for state deferred tax assets		(100)	(6,900)	(3,400)
Effective settlement of prior tax positions			(4,700)
Other		300	(1,400)	(100)
Provision for income tax		5,600	4,900	3,500
Income before provision for income taxes		30,400	89,000	77,200
Deferred tax assets:
Operating lease liabilities		24,900
State net operating losses		9,400	9,000
Credits and incentives		8,200
Employee benefits		8,000	9,400
Deferred revenue		2,300	7,700
Inventory costs		2,800	4,900
Postretirement benefits		5,300	3,700
Other		4,000	4,800
Total deferred tax assets		64,900	39,500
Valuation allowance			(100)
Total deferred tax assets net of valuation allowance		64,900	39,400
Deferred tax liabilities:
Tangible and intangible assets		(35,000)	(36,100)
ROU operating lease assets		26,200
Other		(200)	(200)
Total deferred tax liabilities		(61,400)	(36,300)
Net deferred tax assets		$ 3,500	3,100
Minimum
Deferred tax liabilities:
Period for net operating losses carry forward (in years)		5 years
Maximum
Deferred tax liabilities:
Period for net operating losses carry forward (in years)		20 years
Other Current Assets
Deferred tax liabilities:
Income tax receivable		$ 7,900	1,100
Domestic
Reasons for difference between the provision for income taxes on pre-tax income from the amount computed by applying the U.S. federal statutory tax rate
Income before provision for income taxes		23,600	68,900	58,700
Foreign
Reasons for difference between the provision for income taxes on pre-tax income from the amount computed by applying the U.S. federal statutory tax rate
Income before provision for income taxes		$ 6,800	$ 20,100	$ 18,500