Quarterly report pursuant to Section 13 or 15(d)

Business combinations - Changes in Goodwill (Details)

v3.21.1
Business combinations - Changes in Goodwill (Details)
$ in Thousands
 6 Months Ended
Mar. 31, 2021
USD ($)
Goodwill [Roll Forward]  
Balance at the beginning of the period $ 593,129
Estimated effects of acquisitions 304,048
Foreign currency translation 2,619
Balance at the end of the period 899,796
U.S. Services  
Goodwill [Roll Forward]  
Balance at the beginning of the period 164,472
Estimated effects of acquisitions 0
Foreign currency translation 0
Balance at the end of the period 164,472
U.S. Federal Services  
Goodwill [Roll Forward]  
Balance at the beginning of the period 381,719
Estimated effects of acquisitions 303,465
Foreign currency translation 0
Balance at the end of the period 685,184
Outside the U.S.  
Goodwill [Roll Forward]  
Balance at the beginning of the period 46,938
Estimated effects of acquisitions 583
Foreign currency translation 2,619
Balance at the end of the period $ 50,140