Annual report pursuant to Section 13 and 15(d)

Business combinations and disposals - Narrative (Details)

v3.20.2
Business combinations and disposals - Narrative (Details)
$ in Thousands, $ in Millions, $ in Millions, ₩ in Billions
11 Months Ended 12 Months Ended
Aug. 21, 2020
USD ($)
Aug. 21, 2020
KRW (₩)
May 01, 2020
USD ($)
Feb. 28, 2020
USD ($)
Feb. 28, 2020
AUD ($)
Aug. 16, 2019
USD ($)
Aug. 16, 2019
CAD ($)
Nov. 16, 2018
USD ($)
Sep. 30, 2019
USD ($)
Sep. 30, 2020
USD ($)
segment
Sep. 30, 2019
USD ($)
Sep. 30, 2018
USD ($)
Aug. 21, 2020
KRW (₩)
Feb. 28, 2020
AUD ($)
Business Acquisition [Line Items]                            
Amortization of intangible assets                   $ 35,634 $ 33,054 $ 10,308    
Goodwill                 $ 584,469 593,129 584,469 399,882    
Proceeds from sale of business                   3,250 0 0    
Gain on sale of a business                   $ 1,718 0 0    
Number of business segments | segment                   3        
Q2 Administrators LLC                            
Business Acquisition [Line Items]                            
Proceeds from sale of business     $ 3,100                      
Gain on sale of a business     $ 1,700                      
General Dynamics Information Technology's Citizen Engagement Centers                            
Business Acquisition [Line Items]                            
Cash payment to acquire business               $ 400,000            
Estimated cash consideration               $ 430,700   $ 430,723        
Acquisition-related expenses                     2,700 $ 500    
Intangible assets acquired                   122,300        
Revenue from acquisition                 615,100          
Gross profit from acquisition                 $ 117,400          
Goodwill                   184,640        
Intangible assets                   122,300        
General Dynamics Information Technology's Citizen Engagement Centers | Customer relationships - all contracts except U.S. Census                            
Business Acquisition [Line Items]                            
Intangible assets acquired                   $ 85,300        
Weighted average remaining life of assets not fully amortized                   10 years        
General Dynamics Information Technology's Citizen Engagement Centers | Customer relationships, U.S. decennial census                            
Business Acquisition [Line Items]                            
Weighted average remaining life of assets not fully amortized                   7 years 7 months 6 days        
General Dynamics Information Technology's Citizen Engagement Centers | Customer relationship - U.S. Census                            
Business Acquisition [Line Items]                            
Intangible assets acquired                   $ 37,000        
Weighted average remaining life of assets not fully amortized                   2 years        
General Dynamics Information Technology's Citizen Engagement Centers | Customer relationship - U.S. Census | Pro Forma                            
Business Acquisition [Line Items]                            
Amortization of intangible assets                   $ 18,500 18,500      
GT Hiring Solutions                            
Business Acquisition [Line Items]                            
Cash payment to acquire business           $ 6,200 $ 8.2              
Weighted average remaining life of assets not fully amortized           7 years 7 years              
Share capital acquired (as a percent)           100.00%                
Goodwill           $ 2,100                
Intangible assets           $ 2,200                
InjuryNet                            
Business Acquisition [Line Items]                            
Cash payment to acquire business       $ 4,400 $ 6.7                  
Share capital acquired (as a percent)       100.00%                   100.00%
Goodwill       $ 2,600                    
Intangible assets       900                    
Contingent consideration       $ 2,100                   $ 3.1
Index Root                            
Business Acquisition [Line Items]                            
Cash payment to acquire business $ 5,400 ₩ 6.3                        
Share capital acquired (as a percent) 100.00%                       100.00%  
Goodwill $ 4,600                          
Intangible assets 1,400                          
Contingent consideration $ 900                       ₩ 1.1  
United Kingdom Subsidiary                            
Business Acquisition [Line Items]                            
Purchase of non-controlling interest by parent                     400      
Saudi Arabia Subsidiary                            
Business Acquisition [Line Items]                            
Purchase of non-controlling interest by parent                     $ 200