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Revenues - Schedule of Disaggregation of Revenue (Details) - USD ($) $ in Millions | 3 Months Ended | 6 Months Ended
--- | --- | ---
Apr. 03, 2026 | Mar. 28, 2025 | Apr. 03, 2026 | Mar. 28, 2025
Disaggregation of Revenue [Line Items] |  |  |  |
Total revenues | $ 3,478 | $ 3,491 | $ 6,715 | $ 6,907
United States |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Total revenues | 2,708 | 2,585 | 5,198 | 5,070
International |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Total revenues | 770 | 906 | 1,517 | 1,837
Prime contractor |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Total revenues | 3,143 | 3,100 | 6,047 | 6,142
Subcontractor |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Total revenues | 335 | 391 | 668 | 765
Cost-plus-fee |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Total revenues | 1,987 | 2,249 | 3,832 | 4,415
Fixed-price |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Total revenues | 982 | 807 | 1,910 | 1,638
Time-and-materials |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Total revenues | 509 | 435 | 973 | 854
Department of War and U.S. Intelligence Community |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Total revenues | 1,881 | 1,808 | 3,617 | 3,576
Other U.S. Government Agencies |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Total revenues | 906 | 990 | 1,754 | 2,006
Commercial and International |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Total revenues | 691 | 693 | 1,344 | 1,325
DS |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Total revenues | 1,468 | 1,340 | 2,805 | 2,626
DS | United States |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Total revenues | 1,408 | 1,285 | 2,692 | 2,507
DS | International |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Total revenues | 60 | 55 | 113 | 119
DS | Prime contractor |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Total revenues | 1,381 | 1,215 | 2,640 | 2,379
DS | Subcontractor |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Total revenues | 87 | 125 | 165 | 247
DS | Cost-plus-fee |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Total revenues | 883 | 861 | 1,669 | 1,646
DS | Fixed-price |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Total revenues | 402 | 331 | 782 | 690
DS | Time-and-materials |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Total revenues | 183 | 148 | 354 | 290
DS | Department of War and U.S. Intelligence Community |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Total revenues | 816 | 738 | 1,527 | 1,460
DS | Other U.S. Government Agencies |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Total revenues | 421 | 405 | 821 | 821
DS | Commercial and International |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Total revenues | 231 | 197 | 457 | 345
GES |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Total revenues | 2,010 | 2,151 | 3,910 | 4,281
GES | United States |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Total revenues | 1,300 | 1,300 | 2,506 | 2,563
GES | International |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Total revenues | 710 | 851 | 1,404 | 1,718
GES | Prime contractor |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Total revenues | 1,762 | 1,885 | 3,407 | 3,763
GES | Subcontractor |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Total revenues | 248 | 266 | 503 | 518
GES | Cost-plus-fee |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Total revenues | 1,104 | 1,388 | 2,163 | 2,769
GES | Fixed-price |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Total revenues | 580 | 476 | 1,128 | 948
GES | Time-and-materials |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Total revenues | 326 | 287 | 619 | 564
GES | Department of War and U.S. Intelligence Community |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Total revenues | 1,065 | 1,070 | 2,090 | 2,116
GES | Other U.S. Government Agencies |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Total revenues | 485 | 585 | 933 | 1,185
GES | Commercial and International |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Total revenues | $ 460 | $ 496 | $ 887 | $ 980

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