Earnings Per Share - Calculation of Basic and Diluted Earnings per Share (Detail) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Mar. 31, 2020	Mar. 31, 2019	Mar. 31, 2020	Mar. 31, 2019
Earnings Per Share [Abstract]
Net income	$ 80,577	$ 68,145	$ 227,749	$ 215,574
Weighted-average number of basic shares outstanding during the period	25,078	24,866	25,012	24,819
Dilutive effect of RSUs after application of treasury stock method	400	482	469	550
Weighted-average number of diluted shares outstanding during the period	25,478	25,348	25,481	25,369
Basic earnings per share	$ 3.21	$ 2.74	$ 9.11	$ 8.69
Diluted earnings per share	$ 3.16	$ 2.69	$ 8.94	$ 8.50