Quarterly report pursuant to Section 13 or 15(d)

Business combinations (Details)

v3.6.0.2
Business combinations (Details)
$ in Thousands
3 Months Ended
Feb. 29, 2016
USD ($)
Dec. 15, 2015
USD ($)
company
Dec. 31, 2016
USD ($)
Sep. 30, 2016
USD ($)
Business Acquisition [Line Items]        
Goodwill     $ 393,480 $ 397,558
Ascend Management Innovations LLC        
Business Acquisition [Line Items]        
Percentage of business acquired 100.00%      
Fair value of consideration $ 44,100   44,069  
Recognized identifiable assets acquired and liabilities assumed $ 22,300   22,300  
Weighted average useful life (in years) 18 years      
Goodwill $ 18,000   17,997  
Assessments Australia        
Business Acquisition [Line Items]        
Percentage of business acquired   100.00%    
Recognized identifiable assets acquired and liabilities assumed   $ 400    
Number of businesses acquired | company   3    
Cash payments to acquire businesses   $ 2,600    
Contingent consideration arrangements, range of outcomes, value, high   500    
Human Services        
Business Acquisition [Line Items]        
Goodwill     $ 44,739 $ 45,731
Human Services | Assessments Australia        
Business Acquisition [Line Items]        
Adjustment to goodwill acquired with Ascend   $ 3,000    
Customer relationships | Ascend Management Innovations LLC        
Business Acquisition [Line Items]        
Finite-lived intangible asset, useful life     19 years  
Customer relationships | Assessments Australia        
Business Acquisition [Line Items]        
Finite-lived intangible asset, useful life   6 years