Taxes - Schedule for components for deferred income taxes (Details) - USD ($) $ in Millions	May 31, 2024	May 31, 2023
Deferred tax assets:
Tax uniform capitalization	$ 8.9	$ 18.0
Prepublication expenses	2.0	1.4
Inventory reserves	22.7	20.7
Allowance for credit losses	1.8	2.2
Deferred revenue	5.7	3.8
Stock based compensation	4.8	4.5
Other reserves	5.4	5.9
Postretirement, post employment and pension obligations	1.9	2.2
Tax carryforwards	30.1	25.2
Lease liabilities	28.7	24.2
Other	15.9	13.6
Gross deferred tax assets	127.9	121.7
Valuation allowance	(19.9)	(18.1)
Total deferred tax assets	108.0	103.6
Deferred tax liabilities:
Depreciation and amortization	(41.1)	(45.2)
Lease right-of-use assets	(25.5)	(21.8)
Research and development costs capitalized	(14.2)	(12.1)
Other	(4.1)	(3.5)
Total deferred tax liability	(84.9)	(82.6)
Total net deferred tax assets	$ 23.1	$ 21.0