Revenues - Disaggregation of Revenues (Details) - USD ($) $ in Thousands	3 Months Ended
	Sep. 30, 2026	Sep. 30, 2025
Disaggregation Of Revenue [Line Items]
Revenues	$ 2,474,597	$ 2,287,623
Technology
Disaggregation Of Revenue [Line Items]
Revenues	1,449,336	1,300,732
Expertise
Disaggregation Of Revenue [Line Items]
Revenues	1,025,261	986,891
Prime contractor
Disaggregation Of Revenue [Line Items]
Revenues	2,209,244	2,076,899
Subcontractor
Disaggregation Of Revenue [Line Items]
Revenues	265,353	210,724
Department of War
Disaggregation Of Revenue [Line Items]
Revenues	1,354,257	1,179,626
Intelligence Community
Disaggregation Of Revenue [Line Items]
Revenues	611,977	596,429
Federal civilian agencies
Disaggregation Of Revenue [Line Items]
Revenues	396,398	411,730
Commercial and other
Disaggregation Of Revenue [Line Items]
Revenues	111,965	99,838
Cost-plus-fee
Disaggregation Of Revenue [Line Items]
Revenues	1,306,307	1,382,630
Fixed-price
Disaggregation Of Revenue [Line Items]
Revenues	821,826	611,493
Time-and-materials
Disaggregation Of Revenue [Line Items]
Revenues	346,464	293,500
Domestic
Disaggregation Of Revenue [Line Items]
Revenues	2,398,161	2,210,044
Domestic \| Technology
Disaggregation Of Revenue [Line Items]
Revenues	1,425,297	1,273,700
Domestic \| Expertise
Disaggregation Of Revenue [Line Items]
Revenues	972,864	936,344
Domestic \| Prime contractor
Disaggregation Of Revenue [Line Items]
Revenues	2,144,267	2,006,508
Domestic \| Subcontractor
Disaggregation Of Revenue [Line Items]
Revenues	253,894	203,536
Domestic \| Department of War
Disaggregation Of Revenue [Line Items]
Revenues	1,354,257	1,179,626
Domestic \| Intelligence Community
Disaggregation Of Revenue [Line Items]
Revenues	611,977	596,429
Domestic \| Federal civilian agencies
Disaggregation Of Revenue [Line Items]
Revenues	396,398	411,730
Domestic \| Commercial and other
Disaggregation Of Revenue [Line Items]
Revenues	35,529	22,259
Domestic \| Cost-plus-fee
Disaggregation Of Revenue [Line Items]
Revenues	1,306,307	1,382,630
Domestic \| Fixed-price
Disaggregation Of Revenue [Line Items]
Revenues	774,275	564,825
Domestic \| Time-and-materials
Disaggregation Of Revenue [Line Items]
Revenues	317,579	262,589
International
Disaggregation Of Revenue [Line Items]
Revenues	76,436	77,579
International \| Technology
Disaggregation Of Revenue [Line Items]
Revenues	24,039	27,032
International \| Expertise
Disaggregation Of Revenue [Line Items]
Revenues	52,397	50,547
International \| Prime contractor
Disaggregation Of Revenue [Line Items]
Revenues	64,977	70,391
International \| Subcontractor
Disaggregation Of Revenue [Line Items]
Revenues	11,459	7,188
International \| Department of War
Disaggregation Of Revenue [Line Items]
Revenues	0	0
International \| Intelligence Community
Disaggregation Of Revenue [Line Items]
Revenues	0	0
International \| Federal civilian agencies
Disaggregation Of Revenue [Line Items]
Revenues	0	0
International \| Commercial and other
Disaggregation Of Revenue [Line Items]
Revenues	76,436	77,579
International \| Cost-plus-fee
Disaggregation Of Revenue [Line Items]
Revenues	0	0
International \| Fixed-price
Disaggregation Of Revenue [Line Items]
Revenues	47,551	46,668
International \| Time-and-materials
Disaggregation Of Revenue [Line Items]
Revenues	$ 28,885	$ 30,911