Stock-Based Compensation - Summary of stock-based compensation expense recognized (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Mar. 31, 2016	Mar. 31, 2015	Mar. 31, 2016	Mar. 31, 2015
Stock-based compensation included in indirect costs and selling expenses:
Total stock-based compensation related to RSUs included in indirect costs and selling expense	$ 4,856	$ 3,857	$ 13,329	$ 10,051
Income tax benefit recognized for stock-based compensation expense	$ 1,719	$ 1,378	$ 4,897	$ 3,737