Earnings Per Share (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		9 Months Ended
	Mar. 31, 2017	Mar. 31, 2016	Mar. 31, 2017	Mar. 31, 2016
Numerator:
Net Income	$ 12,424	$ 14,042	$ 50,276	$ 50,694
Denominator:
Weighted-average shares, basic (in shares)	25,262,000	25,863,000	25,311,000	26,741,000
Dilutive effect of share-based payments (in shares)	138,000	104,000	147,000	167,000
Weighted-average shares, diluted (in shares)	25,400,000	25,967,000	25,458,000	26,908,000
Net income per common share, basic (in dollars per share)	$ 0.49	$ 0.54	$ 1.99	$ 1.90
Net income per common share, diluted (in dollars per share)	$ 0.49	$ 0.54	$ 1.97	$ 1.88
Weighted average shares excluded from the computation of diluted earnings per share (in shares)	442,001	868,211	454,006	835,055