Stock-Based Compensation - Summary of stock-based compensation expense recognized (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2013	Dec. 31, 2012
Stock-based compensation included in indirect costs and selling expenses:
Restricted stock and restricted stock unit (RSU) expense.	$ 3,301	$ 3,327	$ 5,744	$ 5,481
Non-qualified stock option and stock settled stock appreciation right (SSAR) expense		174	41	420
Total stock-based compensation expense	3,301	3,501	5,785	5,901
Income tax benefit recognized for stock-based compensation expense	$ 1,278	$ 1,302	$ 2,225	$ 2,216