Segment Information - Reconciliation of Total Segment Profit to Income before Income Taxes (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2017	Dec. 31, 2016
Reconciliation to Income before Income Taxes
Total segment profit for reportable segments	$ 54,465	$ 56,065	$ 107,778	$ 110,796
General and administrative	(14,178)	(11,863)	(27,854)	(25,020)
Other (expense) income, net	(238)	697	(854)	1,344
Income before provision for income taxes	53,006	56,086	104,638	110,866
Operating segments
Reconciliation to Income before Income Taxes
Total segment profit for reportable segments	68,643	67,928	135,632	135,816
Segment Reconciling Items
Reconciliation to Income before Income Taxes
General and administrative	(14,178)	(11,863)	(27,854)	(25,020)
Other (expense) income, net	(238)	697	(854)	1,344
Interest (expense) income, net	$ (1,221)	$ (676)	$ (2,286)	$ (1,274)