Earnings Per Share - Calculation of Basic and Diluted Earnings per Share (Detail) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended
	Sep. 30, 2018	Sep. 30, 2017
Earnings Per Share [Abstract]
Net income	$ 78,833	$ 42,046
Weighted-average number of basic shares outstanding during the period	24,737	24,487
Dilutive effect of RSUs after application of treasury stock method	687	756
Weighted-average number of diluted shares outstanding during the period	25,424	25,243
Basic earnings per share	$ 3.19	$ 1.72
Diluted earnings per share	$ 3.10	$ 1.67