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, 2016	$ 1,607,313	$ 4,176	$ 558,324	$ 1,661,948	$ (41,083)	$ (576,187)	$ 1,607,178	$ 135
Beginning 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
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	265,604			265,604			265,604
Stock-based compensation expense	25,272		25,272				25,272
Tax withholdings on restricted share vesting	(19,555)	$ 17	(19,572)				(19,555)
Tax withholdings on restricted share vesting (in shares)		175
Change in fair value of interest rate swap agreements, net	(17,914)				(17,914)		(17,914)
Currency translation adjustment	(6,103)				(6,103)		(6,103)
Repurchases of common stock	(5,838)		(392)			$ (5,446)	(5,838)
Repurchases of common stock (in shares)						34
Treasury stock issued under stock purchase plans	5,452		5			$ 5,447	5,452
Treasury stock issued under stock purchase plans (in shares)						(34)
Post-retirement benefit costs	(109)				(109)		(109)
Ending balance at Jun. 30, 2019	2,371,466	$ 4,231	$ 576,277	2,410,164	$ (43,156)	$ (576,185)	2,371,331	$ 135
Ending balance, shares at Jun. 30, 2019		42,314				17,434
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Cumulative effect adjustment of ASC 606, net of taxes	$ 17,770			$ 17,770			$ 17,770