BUSINESS SEGMENT, CUSTOMER AND GEOGRAPHIC INFORMATION - Revenue by Customer Sector (Detail 1) - USD ($) $ in Thousands	3 Months Ended									12 Months Ended
	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	[1]	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2016
Revenue, Major Customer [Line Items]
Revenue	$ 1,170,086	$ 1,124,100	$ 1,087,860		$ 1,085,814	$ 1,137,389	$ 1,086,418	$ 1,057,530	$ 1,073,280	$ 4,467,860	$ 4,354,617	$ 3,744,053
Customer Information | Sales
Revenue, Major Customer [Line Items]
Revenue										$ 4,467,860	$ 4,354,617	$ 3,744,053
Percentage of revenue										100.00%	100.00%	100.00%
Customer Information | Department of Defense | Sales
Revenue, Major Customer [Line Items]
Revenue										$ 2,974,578	$ 2,829,305	$ 2,439,329
Percentage of revenue										66.60%	65.00%	65.10%
Customer Information | Federal civilian agencies | Sales
Revenue, Major Customer [Line Items]
Revenue										$ 1,201,874	$ 1,259,212	$ 1,062,508
Percentage of revenue										26.90%	28.90%	28.40%
Customer Information | Commercial and other | Sales
Revenue, Major Customer [Line Items]
Revenue										$ 291,408	$ 266,100	$ 242,216
Percentage of revenue										6.50%	6.10%	6.50%

[1] Net income for the second quarter of FY2018 includes a net benefit related to the TCJA. See Note 19.