Business Segment Information - Summarized Financial Information of Reportable Segments (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Mar. 31, 2017	Mar. 31, 2016	Mar. 31, 2017	Mar. 31, 2016
Segment Reporting Information [Line Items]
Revenue from external customers	$ 1,086,418	$ 977,274	$ 3,217,228	$ 2,630,153
Net income	40,357	34,116	119,440	99,200
Net income attributable to CACI	40,357	34,116	119,440	99,200
Domestic
Segment Reporting Information [Line Items]
Revenue from external customers	1,051,449	940,714	3,114,365	2,519,934
Net income	36,920	30,712
Net income attributable to CACI			109,294	89,388
International
Segment Reporting Information [Line Items]
Revenue from external customers	34,969	36,560	102,863	110,219
Net income	$ 3,437	$ 3,404
Net income attributable to CACI			$ 10,146	$ 9,812