Quarterly report pursuant to Section 13 or 15(d)

Business combinations and disposals (Details)

v3.5.0.2
Business combinations and disposals (Details)
$ in Thousands
3 Months Ended 9 Months Ended
May 09, 2016
USD ($)
Feb. 29, 2016
USD ($)
Dec. 15, 2015
USD ($)
company
Jun. 30, 2016
USD ($)
Jun. 30, 2015
USD ($)
Jun. 30, 2016
USD ($)
Jun. 30, 2015
USD ($)
Sep. 30, 2015
USD ($)
Apr. 01, 2015
Business Acquisition [Line Items]                  
Gain on disposal       $ 6,453 $ 0 $ 6,453 $ 0    
Assets of K-12 Education       1,298,093   1,298,093   $ 1,271,558  
Liabilities of K-12 Education       592,572   592,572   655,859  
Goodwill       398,929   398,929   376,302  
Acentia LLC                  
Business Acquisition [Line Items]                  
Percentage of business acquired                 100.00%
Recognized identifiable assets acquired and liabilities assumed       69,900   69,900      
Goodwill       221,949   221,949      
Ascend Management Innovations LLC                  
Business Acquisition [Line Items]                  
Percentage of business acquired   100.00%              
Fair value of consideration           44,000      
Recognized identifiable assets acquired and liabilities assumed   $ 22,300   22,300   22,300      
Weighted average useful life (in years)   18 years              
Goodwill   $ 18,500   $ 18,495   18,495      
Acquisition of Ascend           18,495      
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     $ 600            
Acquisition of Ascend           2,899      
K-12 Education                  
Business Acquisition [Line Items]                  
Gain on disposal $ 6,500                
Revenue contributed from K-12 Education           $ 2,300 $ 3,500    
Assets of K-12 Education               1,500  
Liabilities of K-12 Education               $ 2,700