Annual report pursuant to Section 13 and 15(d)

Goodwill And Intangiable Assets - Schedule of goodwill (Details)

v3.23.3
Goodwill And Intangiable Assets - Schedule of goodwill (Details) - USD ($)
$ in Thousands
 12 Months Ended
Sep. 30, 2023
Sep. 30, 2022
Sep. 30, 2021
Goodwill [Roll Forward]      
Balance at the beginning of the period $ 1,779,415 $ 1,774,406  
Acquisitions   13,681  
Divestitures (3,172)    
Foreign currency translation 2,972 (8,672)  
Balance at the end of the period 1,779,215 1,779,415 $ 1,774,406
Goodwill, impairment charges 0 0 0
U.S. Federal Services      
Goodwill [Roll Forward]      
Balance at the beginning of the period 1,559,863 1,549,921  
Acquisitions   9,942  
Divestitures 0    
Foreign currency translation 0 0  
Balance at the end of the period 1,559,863 1,559,863 1,549,921
U.S. Services      
Goodwill [Roll Forward]      
Balance at the beginning of the period 164,472 164,472  
Acquisitions   0  
Divestitures 0    
Foreign currency translation 0 0  
Balance at the end of the period 164,472 164,472 164,472
Outside the U.S.      
Goodwill [Roll Forward]      
Balance at the beginning of the period 55,080 60,013  
Acquisitions   3,739  
Divestitures (3,172)    
Foreign currency translation 2,972 (8,672)  
Balance at the end of the period $ 54,880 $ 55,080 $ 60,013