Fair Value - Assets Measured at Fair Value on Non-Recurring Basis (Detail) - Fair Value, Measurements, Nonrecurring - USD ($) $ in Thousands	Aug. 31, 2018	May 31, 2018
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Asset measured at fair value on non-recurring basis	$ 7,000	$ 30,000
Long-lived Assets Held and Used
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Asset measured at fair value on non-recurring basis	7,000	30,000
Significant Other Observable Inputs (Level 2)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Asset measured at fair value on non-recurring basis	7,000	30,000
Significant Other Observable Inputs (Level 2) | Long-lived Assets Held and Used
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Asset measured at fair value on non-recurring basis	$ 7,000	$ 30,000