CONSOLIDATED STATEMENTS OF SHAREHOLDERS' EQUITY - USD ($) shares in Thousands, $ in Thousands	Total	Common Stock	Additional Paid-in Capital	Retained Earnings	Accumulated Other Comprehensive Income (Loss)	Treasury Stock	Total CACI Shareholders' Equity	Noncontrolling Interest
Beginning balance at Jun. 30, 2015	$ 1,480,272	$ 4,162	$ 547,979	$ 1,519,149	$ (14,960)	$ (576,193)	$ 1,480,137	$ 135
Beginning balance, shares at Jun. 30, 2015		41,622				17,438
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	142,799			142,799			142,799
Stock-based compensation expense	17,919		17,919				17,919
Exercise of stock options and vesting of restricted stock units	(7,451)	$ 14	(7,465)				(7,451)
Exercise of stock options and vesting of restricted stock units (in shares)		136
Change in fair value of interest rate swap agreements, net	(5,992)				(5,992)		(5,992)
Currency translation adjustment	(19,961)				(19,961)		(19,961)
Repurchases of common stock	(3,230)		(192)			$ (3,038)	(3,230)
Repurchases of common stock (in shares)						37
Treasury stock issued under stock purchase plans	3,127		83			$ 3,044	3,127
Treasury stock issued under stock purchase plans (in shares)						(40)
Post-retirement benefit costs	(170)				(170)		(170)
Ending balance at Jun. 30, 2016	1,607,313	$ 4,176	558,324	1,661,948	(41,083)	$ (576,187)	1,607,178	135
Ending balance, shares at Jun. 30, 2016		41,758				17,435
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	163,671			163,671			163,671
Stock-based compensation expense	21,945		21,945				21,945
Tax withholdings on restricted share vesting	(10,943)	$ 14	(10,957)				(10,943)
Tax withholdings on restricted share vesting (in shares)		138
Change in fair value of interest rate swap agreements, net	14,587				14,587		14,587
Currency translation adjustment	(2,804)				(2,804)		(2,804)
Repurchases of common stock	(4,386)		(236)			$ (4,150)	(4,386)
Repurchases of common stock (in shares)						41
Treasury stock issued under stock purchase plans	4,154		4			$ 4,150	4,154
Treasury stock issued under stock purchase plans (in shares)						(41)
Post-retirement benefit costs	184				184		184
Ending balance at Jun. 30, 2017	1,793,721	$ 4,190	569,080	1,825,619	(29,116)	$ (576,187)	1,793,586	135
Ending balance, shares at Jun. 30, 2017		41,896				17,435
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	301,171			301,171			301,171
Stock-based compensation expense	23,628		23,628				23,628
Tax withholdings on restricted share vesting	(21,344)	$ 24	(21,368)				(21,344)
Tax withholdings on restricted share vesting (in shares)		243
Change in fair value of interest rate swap agreements, net	7,473				7,473		7,473
Currency translation adjustment	1,986				1,986		1,986
Repurchases of common stock	(5,138)		(383)			$ (4,755)	(5,138)
Repurchases of common stock (in shares)						36
Treasury stock issued under stock purchase plans	4,763		7			$ 4,756	4,763
Treasury stock issued under stock purchase plans (in shares)						(37)
Post-retirement benefit costs	627				627		627
Ending balance at Jun. 30, 2018	$ 2,106,887	$ 4,214	$ 570,964	$ 2,126,790	$ (19,030)	$ (576,186)	$ 2,106,752	$ 135
Ending balance, shares at Jun. 30, 2018		42,139				17,434