Fair value, after effects of master netting arrangements, of financial asset or other contract with one or more underlyings, notional amount or payment provision or both, and the contract can be net settled by means outside the contract or delivery of an asset offset against an obligation to return collateral. Includes assets not subject to a master netting arrangement and not elected to be offset.

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Nominal or face amount used to calculate payments on the derivative liability.

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The number of derivative instruments of a particular group held by the entity.

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Derivative Instruments and Hedging Activities (Details) $ in Millions	Aug. 31, 2015 USD ($) item	May. 31, 2015 USD ($)
Derivative Instruments and Hedging Activities
Number of derivative financial instruments \| item	2
Interest rate cap \| Derivatives designated as hedging instruments: \| Cash flow hedges
Derivative Instruments and Hedging Activities
Notional amount under revolving credit agreement	$ 50.0
Interest rate swap \| Derivatives designated as hedging instruments: \| Cash flow hedges
Derivative Instruments and Hedging Activities
Notional amount under revolving credit agreement	$ 50.0
Interest Rate Swap and Cap Agreements \| Derivatives designated as hedging instruments:
Derivative Instruments and Hedging Activities
Settlement of floating-to-fixed interest rate swap and interest rate cap agreement		$ 2.6