Long-Term Debt, Derivatives and Letters of Credit - Fair Value Totals and Balance Sheet Classification for Derivatives Designated as Hedges (Detail) - USD ($) $ in Thousands	Dec. 31, 2015	May. 31, 2015	May. 31, 2014
Long-term Debt [Member] \| Designated as Hedging Instrument [Member] \| Net Investment Hedge [Member]
Derivatives, Fair Value [Line Items]
Fair value liability	$ (4,567)	$ (4,466)	$ (1,229)

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

No definition available.

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