Quarterly report pursuant to Section 13 or 15(d)

Business combinations - Narrative (Details)

v3.21.1
Business combinations - Narrative (Details)
$ in Thousands, $ in Millions, ₩ in Billions
3 Months Ended 6 Months Ended
Mar. 01, 2021
USD ($)
Aug. 21, 2020
USD ($)
Aug. 21, 2020
KRW (₩)
Feb. 28, 2020
USD ($)
Feb. 28, 2020
AUD ($)
Mar. 31, 2021
USD ($)
Mar. 31, 2020
USD ($)
Mar. 31, 2021
USD ($)
Mar. 31, 2020
USD ($)
Sep. 30, 2020
USD ($)
Aug. 21, 2020
KRW (₩)
Feb. 28, 2020
AUD ($)
Business Acquisition [Line Items]                        
Goodwill           $ 899,796   $ 899,796   $ 593,129    
Revenue           959,280 $ 818,135 1,904,834 $ 1,636,364      
Operating income           113,186 $ 37,311 $ 200,758 $ 116,446      
Weighted Average                        
Business Acquisition [Line Items]                        
Useful life               9 years 2 months 12 days        
Weighted Average | Customer contracts and relationships                        
Business Acquisition [Line Items]                        
Useful life 9 years 2 months 12 days                      
Weighted Average | Technology based intangible assets                        
Business Acquisition [Line Items]                        
Useful life               2 years 7 months 6 days        
Attain                        
Business Acquisition [Line Items]                        
Estimated cash consideration $ 419,864                      
Goodwill 303,465                      
Revenue           19,900   $ 19,900        
Operating income           3,000   $ 3,000        
Intangible assets 105,000                      
Attain | Customer Relationships                        
Business Acquisition [Line Items]                        
Intangible assets acquired $ 105,000                      
Useful life 10 years                      
Attain | Line of Credit                        
Business Acquisition [Line Items]                        
Proceeds from lines of credit $ 240,000                      
InjuryNet                        
Business Acquisition [Line Items]                        
Goodwill       $ 2,600                
Percentage of voting equity interests acquired       100.00%               100.00%
Cash payment to acquire business       $ 4,400 $ 6.7              
Contingent consideration       2,100               $ 3.1
Intangible assets       $ 900                
Index Root                        
Business Acquisition [Line Items]                        
Goodwill   $ 4,600                    
Percentage of voting equity interests acquired   100.00%                 100.00%  
Cash payment to acquire business   $ 5,400 ₩ 6.3                  
Contingent consideration   900                 ₩ 1.1  
Intangible assets   $ 1,400                    
Reversal of acquisition related costs           $ 1,000