Accounts Receivable (Details) - USD ($) $ in Millions	Aug. 31, 2021	May 31, 2021
Accounts Receivable
Accounts receivable	$ 180.8	$ 166.7
Past due accounts receivable	2.2
Allowance for doubtful accounts	5.0
U.S. Government Contract
Accounts Receivable
Accounts receivable	44.2	49.3
Unbilled receivables	21.2	25.2
U.S. Government Contract \| Trade receivables
Accounts Receivable
Accounts receivable	23.0	24.1
All other customers
Accounts Receivable
Accounts receivable	136.6	117.4
Unbilled receivables	16.1	12.5
All other customers \| Trade receivables
Accounts Receivable
Accounts receivable	$ 120.5	$ 104.9

Amount, after allowance for credit loss, of right to consideration from customer for product sold and service rendered in normal course of business, classified as current.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
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-Section 45
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Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
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-Paragraph 1
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Reference 3: http://www.xbrl.org/2003/role/exampleRef
-Publisher FASB
-Name Accounting Standards Codification
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Reference 4: http://www.xbrl.org/2003/role/disclosureRef
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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant