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Revenues - Schedule of Disaggregation of Revenue (Details) - USD ($) $ in Millions | 12 Months Ended
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Oct. 03, 2025 | Sep. 27, 2024 | Sep. 29, 2023
Disaggregation of Revenue [Line Items] |  |  |
Total revenues | $ 14,393 | $ 8,388 | $ 7,865
DS |  |  |
Disaggregation of Revenue [Line Items] |  |  |
Total revenues | 5,543 | 1,981 | 1,899
GES |  |  |
Disaggregation of Revenue [Line Items] |  |  |
Total revenues | 8,850 | 6,407 | 5,966
Department of War and U.S. Intelligence Community |  |  |
Disaggregation of Revenue [Line Items] |  |  |
Total revenues | 7,678 | 5,603 | 5,265
Department of War and U.S. Intelligence Community | DS |  |  |
Disaggregation of Revenue [Line Items] |  |  |
Total revenues | 3,222 | 1,509 | 1,474
Department of War and U.S. Intelligence Community | GES |  |  |
Disaggregation of Revenue [Line Items] |  |  |
Total revenues | 4,456 | 4,094 | 3,791
Other U.S. Government Agencies |  |  |
Disaggregation of Revenue [Line Items] |  |  |
Total revenues | 3,994 | 1,984 | 1,867
Other U.S. Government Agencies | DS |  |  |
Disaggregation of Revenue [Line Items] |  |  |
Total revenues | 1,607 | 386 | 341
Other U.S. Government Agencies | GES |  |  |
Disaggregation of Revenue [Line Items] |  |  |
Total revenues | 2,387 | 1,598 | 1,526
Commercial and International |  |  |
Disaggregation of Revenue [Line Items] |  |  |
Total revenues | 2,721 | 801 | 733
Commercial and International | DS |  |  |
Disaggregation of Revenue [Line Items] |  |  |
Total revenues | 714 | 86 | 84
Commercial and International | GES |  |  |
Disaggregation of Revenue [Line Items] |  |  |
Total revenues | 2,007 | 715 | 649
United States |  |  |
Disaggregation of Revenue [Line Items] |  |  |
Total revenues | 10,746 | 6,055 | 5,748
United States | DS |  |  |
Disaggregation of Revenue [Line Items] |  |  |
Total revenues | 5,304 | 1,679 | 1,544
United States | GES |  |  |
Disaggregation of Revenue [Line Items] |  |  |
Total revenues | 5,442 | 4,376 | 4,204
International |  |  |
Disaggregation of Revenue [Line Items] |  |  |
Total revenues | 3,647 | 2,333 | 2,117
International | DS |  |  |
Disaggregation of Revenue [Line Items] |  |  |
Total revenues | 239 | 302 | 355
International | GES |  |  |
Disaggregation of Revenue [Line Items] |  |  |
Total revenues | 3,408 | 2,031 | 1,762
Prime contractor |  |  |
Disaggregation of Revenue [Line Items] |  |  |
Total revenues | 13,096 | 7,510 | 6,958
Prime contractor | DS |  |  |
Disaggregation of Revenue [Line Items] |  |  |
Total revenues | 5,069 | 1,772 | 1,722
Prime contractor | GES |  |  |
Disaggregation of Revenue [Line Items] |  |  |
Total revenues | 8,027 | 5,738 | 5,236
Subcontractor |  |  |
Disaggregation of Revenue [Line Items] |  |  |
Total revenues | 1,297 | 878 | 907
Subcontractor | DS |  |  |
Disaggregation of Revenue [Line Items] |  |  |
Total revenues | 474 | 209 | 177
Subcontractor | GES |  |  |
Disaggregation of Revenue [Line Items] |  |  |
Total revenues | 823 | 669 | 730
Cost-plus-fee |  |  |
Disaggregation of Revenue [Line Items] |  |  |
Total revenues | 8,983 | 5,198 | 4,941
Cost-plus-fee | DS |  |  |
Disaggregation of Revenue [Line Items] |  |  |
Total revenues | 3,557 | 964 | 875
Cost-plus-fee | GES |  |  |
Disaggregation of Revenue [Line Items] |  |  |
Total revenues | 5,426 | 4,234 | 4,066
Fixed-price |  |  |
Disaggregation of Revenue [Line Items] |  |  |
Total revenues | 3,489 | 2,226 | 2,089
Fixed-price | DS |  |  |
Disaggregation of Revenue [Line Items] |  |  |
Total revenues | 1,422 | 650 | 667
Fixed-price | GES |  |  |
Disaggregation of Revenue [Line Items] |  |  |
Total revenues | 2,067 | 1,576 | 1,422
Time-and-materials |  |  |
Disaggregation of Revenue [Line Items] |  |  |
Total revenues | 1,921 | 964 | 835
Time-and-materials | DS |  |  |
Disaggregation of Revenue [Line Items] |  |  |
Total revenues | 564 | 367 | 357
Time-and-materials | GES |  |  |
Disaggregation of Revenue [Line Items] |  |  |
Total revenues | $ 1,357 | $ 597 | $ 478

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