Summary of Significant Accounting Policies and New Accounting Standards (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Mar. 31, 2017	Mar. 31, 2016	Mar. 31, 2017	Mar. 31, 2016
Accounting Policies [Abstract]
Net income	$ 23,643	$ 18,577	$ 49,237	$ 67,508
Weighted average number of shares - basic (in shares)	39,512	39,356	39,443	39,203
Dilutive effect of stock options	547	644	545	793
Weighted average number of shares - diluted (in shares)	40,059	40,000	39,988	39,996
Net income per share
basic (in dollars per share)	$ 0.60	$ 0.47	$ 1.25	$ 1.72
diluted (in dollars per share)	$ 0.59	$ 0.46	$ 1.23	$ 1.69