Business Segment Information - Summarized Financial Information of Reportable Segments (Detail) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2016	Dec. 31, 2015
Segment Reporting Information [Line Items]
Revenue from external customers	$ 1,057,530	$ 830,437	$ 2,130,810	$ 1,652,879
Net income	42,420	30,452	79,083	65,084
Net income attributable to CACI	42,420	30,452	79,083	65,084
Domestic
Segment Reporting Information [Line Items]
Revenue from external customers	1,024,025	793,542	2,062,916	1,579,220
Net income	38,732	26,741
Net income attributable to CACI			72,374	58,676
International
Segment Reporting Information [Line Items]
Revenue from external customers	33,505	36,895	67,894	73,659
Net income	$ 3,688	$ 3,711
Net income attributable to CACI			$ 6,709	$ 6,408