Annual report pursuant to Section 13 and 15(d)

Business combinations and disposal - Narrative (Details)

v3.19.3
Business combinations and disposal - Narrative (Details)
$ in Thousands, $ in Millions
1 Months Ended 9 Months Ended 12 Months Ended
Aug. 16, 2019
CAD ($)
Aug. 16, 2019
USD ($)
Nov. 16, 2018
USD ($)
Jul. 18, 2017
USD ($)
May 31, 2017
USD ($)
Jun. 30, 2019
USD ($)
Sep. 30, 2019
USD ($)
Sep. 30, 2018
USD ($)
Sep. 30, 2017
USD ($)
Business Acquisition [Line Items]                  
Goodwill             $ 584,469 $ 399,882 $ 402,976
Amortization of intangible assets             33,054 10,308 12,208
Gain on sale of a business             0 0 $ 650
General Dynamics Information Technology's Citizen Engagement Centers                  
Business Acquisition [Line Items]                  
Cash payment to acquire business     $ 400,000            
Estimated cash consideration     430,700     $ 430,699 430,723    
Acquisition-related expenses             2,700 500  
Payments to acquire software licenses             4,500    
Goodwill           184,614 184,640    
Intangible assets acquired             122,300    
Revenue from acquiree since date of acquisition             615,100    
Gross profit from acquiree since date of acquisition             117,400    
Intangible assets           $ 122,300 122,300    
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  
General Dynamics Information Technology's Citizen Engagement Centers | Line of Credit                  
Business Acquisition [Line Items]                  
Proceeds from long-term lines of credit     150,000            
GT Hiring Solutions                  
Business Acquisition [Line Items]                  
Cash payment to acquire business $ 8.1 $ 6,100              
Goodwill     1,700            
Share capital acquired (as a percent) 100.00% 100.00%              
Intangible assets     $ 2,700            
Revitalised                  
Business Acquisition [Line Items]                  
Cash payment to acquire business       $ 4,000          
Goodwill       $ 2,800          
Share capital acquired (as a percent)       100.00%          
Intangible assets       $ 1,300          
Disposal Group, Disposed of by Sale, Not Discontinued Operations | Related to Disposition of K-12 Education | K-12 Education                  
Business Acquisition [Line Items]                  
Gain on sale of a business         $ 700        
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