Accounting Policies [Line Items]

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- Definition

Accounts Notes And Loans Receivable Gross Current

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No definition available.

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- Definition

Advance Collections Current

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No definition available.

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- Definition

Number of Clients Creating a Credit Concentration

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No definition available.

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- Definition

Maximum Individual Claims Liability Health Insurance

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No definition available.

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- Definition

Maximum individual claims liability workers compensation insurance.

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No definition available.

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- Definition

Amount of expense for award under share-based payment arrangement. Excludes amount capitalized.

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- Definition

Amount of allowance for credit loss on accounts receivable, classified as current.

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- Definition

For an entity that discloses a concentration risk in relation to quantitative amount, which serves as the "benchmark" (or denominator) in the equation, this concept represents the concentration percentage derived from the division.

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- Definition

Number of segments reported by the entity. A reportable segment is a component of an entity for which there is an accounting requirement to report separate financial information on that component in the entity's financial statements.

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Description of Business, Basis of Presentation, and Significant Accounting Policies (Narrative) (Details) $ in Millions		3 Months Ended		9 Months Ended		12 Months Ended
	Feb. 28, 2021 USD ($) item	Feb. 28, 2021 USD ($) item	Feb. 29, 2020 USD ($) item	Feb. 28, 2021 USD ($) item segment	Feb. 29, 2020 USD ($) item	May 31, 2021 USD ($)	May 31, 2020 USD ($) item
Accounting Policies [Line Items]
Number of reportable segments \| segment				1
Allowance for doubtful accounts	$ 20.3	$ 20.3		$ 20.3			$ 12.5
Advance collections	3.8	3.8		3.8			6.1
Maximum individual health insurance claims liability							0.3
Stock-based compensation expense		12.6	$ 12.7	38.1	$ 36.5
Forecast [Member]
Accounting Policies [Line Items]
Maximum individual health insurance claims liability						$ 0.3
Trade Receivables [Member]
Accounting Policies [Line Items]
Receivables	99.3	99.3		99.3			84.7
Purchased Receivables [Member]
Accounting Policies [Line Items]
Receivables	$ 615.8	$ 615.8		$ 615.8			$ 311.9
Revenue [Member]
Accounting Policies [Line Items]
Number of clients creating a credit concentration \| item		0	0	0	0
Concentration percentage		10.00%	10.00%	10.00%	10.00%
Accounts Receivable And Unbilled Receivables [Member]
Accounting Policies [Line Items]
Number of clients creating a credit concentration \| item	1						0
Concentration percentage	13.00%						10.00%
PEO [Member]
Accounting Policies [Line Items]
Maximum individual workers' compensation claims liability							$ 1.0
PEO [Member] \| Forecast [Member]
Accounting Policies [Line Items]
Maximum individual workers' compensation claims liability						$ 1.0