Subsequent Events - Additional Information (Detail) - USD ($)	May 31, 2017	May 31, 2016
Subsequent Event [Line Items]
Stock repurchase program, period		6 months
Maximum [Member]
Subsequent Event [Line Items]
Amount authorized under stock repurchase program		$ 75,000,000
Subsequent Event [Member]
Subsequent Event [Line Items]
Stock repurchase program, period	12 months
Stock repurchase program, commencing date	Jul. 01, 2017
Subsequent Event [Member] | Maximum [Member]
Subsequent Event [Line Items]
Amount authorized under stock repurchase program	$ 50,000,000