Revenues - Schedule of Disaggregated Revenues (Details) - USD ($) $ in Thousands	12 Months Ended
	Jun. 30, 2026	Jun. 30, 2025	Jun. 30, 2024
Disaggregation Of Revenue [Line Items]
Revenues	$ 9,567,779	$ 8,627,824	$ 7,659,832
Technology
Disaggregation Of Revenue [Line Items]
Revenues	5,583,122	4,777,983	4,102,843
Expertise
Disaggregation Of Revenue [Line Items]
Revenues	3,984,657	3,849,841	3,556,989
Prime contractor
Disaggregation Of Revenue [Line Items]
Revenues	8,619,301	7,783,908	6,849,849
Subcontractor
Disaggregation Of Revenue [Line Items]
Revenues	948,478	843,916	809,983
Department of War
Disaggregation Of Revenue [Line Items]
Revenues	5,133,759	4,617,699	4,065,974
Intelligence Community
Disaggregation Of Revenue [Line Items]
Revenues	2,351,801	2,209,238	1,954,137
Federal civilian agencies
Disaggregation Of Revenue [Line Items]
Revenues	1,660,934	1,433,013	1,266,320
Commercial and other
Disaggregation Of Revenue [Line Items]
Revenues	421,285	367,874	373,401
Cost-plus-fee
Disaggregation Of Revenue [Line Items]
Revenues	5,361,366	5,221,011	4,654,689
Fixed-price
Disaggregation Of Revenue [Line Items]
Revenues	2,901,065	2,271,602	2,091,179
Time-and-materials
Disaggregation Of Revenue [Line Items]
Revenues	1,305,348	1,135,211	913,964
Domestic
Disaggregation Of Revenue [Line Items]
Revenues	9,260,288	8,370,361	7,432,745
Domestic \| Technology
Disaggregation Of Revenue [Line Items]
Revenues	5,478,482	4,655,816	3,959,311
Domestic \| Expertise
Disaggregation Of Revenue [Line Items]
Revenues	3,781,806	3,714,545	3,473,434
Domestic \| Prime contractor
Disaggregation Of Revenue [Line Items]
Revenues	8,347,308	7,553,566	6,649,114
Domestic \| Subcontractor
Disaggregation Of Revenue [Line Items]
Revenues	912,980	816,795	783,631
Domestic \| Department of War
Disaggregation Of Revenue [Line Items]
Revenues	5,133,759	4,617,699	4,065,974
Domestic \| Intelligence Community
Disaggregation Of Revenue [Line Items]
Revenues	2,351,801	2,209,238	1,954,137
Domestic \| Federal civilian agencies
Disaggregation Of Revenue [Line Items]
Revenues	1,660,934	1,433,013	1,266,320
Domestic \| Commercial and other
Disaggregation Of Revenue [Line Items]
Revenues	113,794	110,411	146,314
Domestic \| Cost-plus-fee
Disaggregation Of Revenue [Line Items]
Revenues	5,361,366	5,221,011	4,654,689
Domestic \| Fixed-price
Disaggregation Of Revenue [Line Items]
Revenues	2,718,362	2,112,490	1,950,286
Domestic \| Time-and-materials
Disaggregation Of Revenue [Line Items]
Revenues	1,180,560	1,036,860	827,770
International
Disaggregation Of Revenue [Line Items]
Revenues	307,491	257,463	227,087
International \| Technology
Disaggregation Of Revenue [Line Items]
Revenues	104,640	122,167	143,532
International \| Expertise
Disaggregation Of Revenue [Line Items]
Revenues	202,851	135,296	83,555
International \| Prime contractor
Disaggregation Of Revenue [Line Items]
Revenues	271,993	230,342	200,735
International \| Subcontractor
Disaggregation Of Revenue [Line Items]
Revenues	35,498	27,121	26,352
International \| Department of War
Disaggregation Of Revenue [Line Items]
Revenues	0	0	0
International \| Intelligence Community
Disaggregation Of Revenue [Line Items]
Revenues	0	0	0
International \| Federal civilian agencies
Disaggregation Of Revenue [Line Items]
Revenues	0	0	0
International \| Commercial and other
Disaggregation Of Revenue [Line Items]
Revenues	307,491	257,463	227,087
International \| Cost-plus-fee
Disaggregation Of Revenue [Line Items]
Revenues	0	0	0
International \| Fixed-price
Disaggregation Of Revenue [Line Items]
Revenues	182,703	159,112	140,893
International \| Time-and-materials
Disaggregation Of Revenue [Line Items]
Revenues	$ 124,788	$ 98,351	$ 86,194