Revenues - Disaggregation of Revenue (Detail) - USD ($) $ in Thousands	12 Months Ended
	Jun. 30, 2022	Jun. 30, 2021	Jun. 30, 2020
Disaggregation Of Revenue [Line Items]
Revenues	$ 6,202,917	$ 6,044,135	$ 5,720,042
Expertise
Disaggregation Of Revenue [Line Items]
Revenues	2,869,317	2,972,966	3,001,512
Technology
Disaggregation Of Revenue [Line Items]
Revenues	3,333,600	3,071,169	2,718,530
Prime contractor
Disaggregation Of Revenue [Line Items]
Revenues	5,564,922	5,449,590	5,211,366
Subcontractor
Disaggregation Of Revenue [Line Items]
Revenues	637,995	594,545	508,676
Department of Defense
Disaggregation Of Revenue [Line Items]
Revenues	4,331,327	4,185,292	3,999,261
Federal civilian agencies
Disaggregation Of Revenue [Line Items]
Revenues	1,549,791	1,585,672	1,467,801
Commercial and other
Disaggregation Of Revenue [Line Items]
Revenues	321,799	273,171	252,980
Cost-plus-fee
Disaggregation Of Revenue [Line Items]
Revenues	3,632,359	3,504,838	3,274,707
Fixed-price
Disaggregation Of Revenue [Line Items]
Revenues	1,823,221	1,769,841	1,629,475
Time and materials
Disaggregation Of Revenue [Line Items]
Revenues	747,337	769,456	815,860
Domestic
Disaggregation Of Revenue [Line Items]
Revenues	6,011,059	5,868,392	5,556,672
Domestic | Expertise
Disaggregation Of Revenue [Line Items]
Revenues	2,796,038	2,901,204	2,938,379
Domestic | Technology
Disaggregation Of Revenue [Line Items]
Revenues	3,215,021	2,967,188	2,618,293
Domestic | Prime contractor
Disaggregation Of Revenue [Line Items]
Revenues	5,389,870	5,284,761	5,057,930
Domestic | Subcontractor
Disaggregation Of Revenue [Line Items]
Revenues	621,189	583,631	498,742
Domestic | Department of Defense
Disaggregation Of Revenue [Line Items]
Revenues	4,331,327	4,185,292	3,999,261
Domestic | Federal civilian agencies
Disaggregation Of Revenue [Line Items]
Revenues	1,549,791	1,585,672	1,467,801
Domestic | Commercial and other
Disaggregation Of Revenue [Line Items]
Revenues	129,941	97,428	89,610
Domestic | Cost-plus-fee
Disaggregation Of Revenue [Line Items]
Revenues	3,632,359	3,504,838	3,274,707
Domestic | Fixed-price
Disaggregation Of Revenue [Line Items]
Revenues	1,690,480	1,651,343	1,524,381
Domestic | Time and materials
Disaggregation Of Revenue [Line Items]
Revenues	688,220	712,211	757,584
International
Disaggregation Of Revenue [Line Items]
Revenues	191,858	175,743	163,370
International | Expertise
Disaggregation Of Revenue [Line Items]
Revenues	73,279	71,762	63,133
International | Technology
Disaggregation Of Revenue [Line Items]
Revenues	118,579	103,981	100,237
International | Prime contractor
Disaggregation Of Revenue [Line Items]
Revenues	175,052	164,829	153,436
International | Subcontractor
Disaggregation Of Revenue [Line Items]
Revenues	16,806	10,914	9,934
International | Commercial and other
Disaggregation Of Revenue [Line Items]
Revenues	191,858	175,743	163,370
International | Fixed-price
Disaggregation Of Revenue [Line Items]
Revenues	132,741	118,498	105,094
International | Time and materials
Disaggregation Of Revenue [Line Items]
Revenues	$ 59,117	$ 57,245	$ 58,276