Fair Value Measurements - Schedule of Fair Value of Financial Instruments Measured on a Recurring Basis (Details) - Fair Value, Measurements, Recurring - USD ($) $ in Thousands	Aug. 31, 2018	May 31, 2018
Fair value on a recurring basis
Cash and cash equivalents	$ 118,356	$ 138,724
Total assets at fair value	118,356	138,724
Total liabilities at fair value	4,169
Interest rate lock agreements
Fair value on a recurring basis
Total liabilities at fair value	4,169
Level 1
Fair value on a recurring basis
Cash and cash equivalents	118,356	138,724
Total assets at fair value	118,356	138,724
Total liabilities at fair value	0
Level 1 | Interest rate lock agreements
Fair value on a recurring basis
Total liabilities at fair value	0
Level 2
Fair value on a recurring basis
Cash and cash equivalents	0	0
Total assets at fair value	0	0
Total liabilities at fair value	4,169
Level 2 | Interest rate lock agreements
Fair value on a recurring basis
Total liabilities at fair value	4,169
Level 3
Fair value on a recurring basis
Cash and cash equivalents	0	0
Total assets at fair value	0	$ 0
Total liabilities at fair value	0
Level 3 | Interest rate lock agreements
Fair value on a recurring basis
Total liabilities at fair value	$ 0