v3.26.1
Business Segments - Schedule of Results of Operations by Business Segment (Details) - USD ($)
$ in Thousands
 3 Months Ended 9 Months Ended
Jun. 30, 2026
Jun. 30, 2025
Jun. 30, 2026
Jun. 30, 2025
Financial information for each of the Company's business segments        
Revenue $ 1,278,971 $ 1,348,400 $ 3,929,984 $ 4,112,861
Cost of revenue 930,168 988,887 2,920,247 3,112,970
Gross profit 348,803 359,513 1,009,737 999,891
Other segment items 168,368 170,754 503,454 485,481
Segment operating income/(loss) 180,435 188,759 506,283 514,410
Divestiture-related gains/(charges)     10,147 (39,343)
Amortization of intangible assets (20,187) (23,010) (60,785) (69,041)
Operating income 161,428 165,672 456,125 405,427
Depreciation and amortization 11,874 9,607 37,091 27,502
Operating Segments | U.S. Federal Services        
Financial information for each of the Company's business segments        
Revenue 720,991 761,174 2,260,735 2,319,756
Cost of revenue $ 498,720 $ 535,040 $ 1,598,084 $ 1,718,249
Cost of revenue (as a percent) 69.20% 70.30% 70.70% 74.10%
Gross profit $ 222,271 $ 226,134 $ 662,651 $ 601,507
Gross profit (as a percent) 30.80% 29.70% 29.30% 25.90%
Other segment items $ 88,231 $ 88,272 $ 266,174 $ 245,563
Other segment items (as a percent) 12.20% 11.60% 11.80% 10.60%
Segment operating income/(loss) $ 134,040 $ 137,862 $ 396,477 $ 355,944
Segment operating income/(loss) (as a percent) 18.60% 18.10% 17.50% 15.30%
Depreciation and amortization $ 7,223 $ 3,125 $ 21,637 $ 9,653
Depreciation and amortization (as a percent) 1.00% 0.40% 1.00% 0.40%
Operating Segments | U.S. Services        
Financial information for each of the Company's business segments        
Revenue $ 418,227 $ 439,818 $ 1,249,229 $ 1,334,418
Cost of revenue $ 311,449 $ 333,886 $ 957,548 $ 1,021,712
Cost of revenue (as a percent) 74.50% 75.90% 76.70% 76.60%
Gross profit $ 106,778 $ 105,932 $ 291,681 $ 312,706
Gross profit (as a percent) 25.50% 24.10% 23.30% 23.40%
Other segment items $ 61,589 $ 60,975 $ 178,616 $ 173,096
Other segment items (as a percent) 14.70% 13.90% 14.30% 13.00%
Segment operating income/(loss) $ 45,189 $ 44,957 $ 113,065 $ 139,610
Segment operating income/(loss) (as a percent) 10.80% 10.20% 9.10% 10.50%
Depreciation and amortization $ 3,997 $ 4,631 $ 12,381 $ 12,603
Depreciation and amortization (as a percent) 1.00% 1.10% 1.00% 0.90%
Operating Segments | Outside the U.S.        
Financial information for each of the Company's business segments        
Revenue $ 139,753 $ 147,408 $ 420,020 $ 458,687
Cost of revenue $ 119,999 $ 119,961 $ 364,615 $ 373,009
Cost of revenue (as a percent) 85.90% 81.40% 86.80% 81.30%
Gross profit $ 19,754 $ 27,447 $ 55,405 $ 85,678
Gross profit (as a percent) 14.10% 18.60% 13.20% 18.70%
Other segment items $ 18,548 $ 21,507 $ 58,664 $ 66,822
Other segment items (as a percent) 13.30% 14.60% 14.00% 14.60%
Segment operating income/(loss) $ 1,206 $ 5,940 $ (3,259) $ 18,856
Segment operating income/(loss) (as a percent) 0.90% 4.00% (0.80%) 4.10%
Depreciation and amortization $ 654 $ 1,851 $ 3,073 $ 5,246
Depreciation and amortization (as a percent) 0.50% 1.30% 0.70% 1.10%
Segment Reconciling Items        
Financial information for each of the Company's business segments        
Divestiture-related gains/(charges) $ 1,162   $ 10,147 $ (39,343)
Other 18 $ (77) 480 (599)
Amortization of intangible assets $ (20,187) $ (23,010) $ (60,785) $ (69,041)