Quarterly report pursuant to Section 13 or 15(d)

Business combinations and disposals (Schedule of Assets and Liabilities Recorded in the Company's Financial Statements) (Details)

v3.7.0.1
Business combinations and disposals (Schedule of Assets and Liabilities Recorded in the Company's Financial Statements) (Details) - USD ($)
$ in Thousands
 9 Months Ended 12 Months Ended
Jun. 30, 2017
Sep. 30, 2016
Feb. 29, 2016
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Net [Abstract]      
Goodwill $ 397,386 $ 397,558  
Ascend Management Innovations LLC      
Business Combination, Consideration Transferred [Abstract]      
Cash consideration, net of cash acquired 44,069    
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Net [Abstract]      
Billed and unbilled receivables 4,069    
Other assets 407    
Property and equipment and other assets 707    
Deferred income taxes 557    
Intangible assets 22,300   $ 22,300
Total identifiable assets acquired 28,040    
Accounts payable and other liabilities 1,414    
Deferred revenue 554    
Total liabilities assumed 1,968    
Net identifiable assets acquired 26,072    
Goodwill 17,997   $ 18,000
Net assets acquired 44,069    
Previously Reported | Ascend Management Innovations LLC      
Business Combination, Consideration Transferred [Abstract]      
Cash consideration, net of cash acquired   44,069  
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Net [Abstract]      
Billed and unbilled receivables   4,069  
Other assets   407  
Property and equipment and other assets   707  
Deferred income taxes   0  
Intangible assets   22,300  
Total identifiable assets acquired   27,483  
Accounts payable and other liabilities   1,414  
Deferred revenue   554  
Total liabilities assumed   1,968  
Net identifiable assets acquired   25,515  
Goodwill   18,554  
Net assets acquired   $ 44,069  
Purchase Accounting Adjustment | Ascend Management Innovations LLC      
Business Combination, Consideration Transferred [Abstract]      
Adjustments, cash consideration, net of cash acquired 0    
Business Combination, Provisional Information, Initial Accounting Incomplete, Adjustments [Abstract]      
Adjustments, billed and unbilled receivables 0    
Adjustments, other noncurrent assets 0    
Adjustments, property and equipment and other assets 0    
Adjustments, deferred income taxes 557    
Adjustments, intangible assets 0    
Adjustments, total identifiable assets acquired 557    
Adjustments, accounts payable and other liabilities 0    
Adjustments, deferred revenue 0    
Adjustments, total liabilities assumed 0    
Adjustments, net identified assets acquired 557    
Adjustments, goodwill (557)    
Adjustments, net assets acquired $ 0