Annual report pursuant to Section 13 and 15(d)

Business combinations and disposals - Acquisition Related Contingent Consideration (Details)

v3.5.0.2
Business combinations and disposals - Acquisition Related Contingent Consideration (Details)
3 Months Ended 12 Months Ended
Sep. 30, 2016
USD ($)
Jun. 30, 2016
USD ($)
Mar. 31, 2016
USD ($)
Dec. 31, 2015
USD ($)
Sep. 30, 2015
USD ($)
Jun. 30, 2015
USD ($)
Mar. 31, 2015
USD ($)
Dec. 31, 2014
USD ($)
Sep. 30, 2016
USD ($)
Sep. 30, 2015
USD ($)
Sep. 30, 2014
USD ($)
Sep. 30, 2016
CAD
Dec. 15, 2015
USD ($)
Sep. 30, 2015
CAD
Dec. 31, 2010
CAD
Business combinations                              
Revenue $ 623,091,000 $ 617,094,000 $ 606,453,000 $ 556,722,000 $ 578,683,000 $ 572,301,000 $ 481,794,000 $ 467,043,000 $ 2,403,360,000 $ 2,099,821,000 $ 1,700,912,000        
DeltaWare | Sales targets                              
Business combinations                              
Contingent consideration arrangements, range of outcomes, value, high | CAD                             CAD 4,000,000
Revenue                 0            
Liability for potential obligation | CAD                       CAD 0   CAD 0  
Assessments Australia                              
Business combinations                              
Contingent consideration arrangements, range of outcomes, value, high                         $ 500,000    
Contingent consideration, liability $ 400,000               $ 400,000