Quarterly report pursuant to Section 13 or 15(d)

Business combinations (Details)

v3.4.0.3
Business combinations (Details)
$ in Thousands
3 Months Ended 6 Months Ended
Feb. 29, 2016
USD ($)
Dec. 15, 2015
USD ($)
company
Mar. 31, 2016
USD ($)
Mar. 31, 2015
USD ($)
Mar. 31, 2016
USD ($)
Mar. 31, 2015
USD ($)
Sep. 30, 2015
USD ($)
Apr. 01, 2015
Business Acquisition [Line Items]                
Goodwill     $ 401,152   $ 401,152   $ 376,302  
Acquisition-related expenses     529 $ 1,514 575 $ 2,114    
Revenue     606,453 481,794 1,163,175 948,837    
Operating income     77,900 $ 62,007 120,686 $ 127,238    
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%              
Cash payments to acquire businesses         39,273      
Contingent consideration arrangements, range of outcomes, value, high $ 5,000              
Recognized identifiable assets acquired and liabilities assumed     22,300   22,300      
Weighted average useful life (in years) 18 years              
Goodwill     16,410   16,410      
Acquisition-related expenses         400      
Revenue     2,100   2,100      
Operating income     200   200      
Assessments Australia                
Business Acquisition [Line Items]                
Percentage of business acquired   100.00%            
Cash payments to acquire businesses         2,569      
Contingent consideration arrangements, range of outcomes, value, high   $ 600            
Recognized identifiable assets acquired and liabilities assumed     365   365      
Goodwill     $ 2,570   $ 2,570      
Number of businesses acquired | company   3