| 
           Business combinations (Details) 
         | 
        9 Months Ended | 0 Months Ended | 9 Months Ended | 0 Months Ended | 3 Months Ended | 0 Months Ended | ||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| 
           Jun. 30, 2014
 
          USD ($) 
         | 
        
           Sep. 30, 2013
 
          USD ($) 
         | 
        
           Jul. 01, 2013
 
          Health Management Limited [Member]
 
          USD ($) 
         | 
        
           Jul. 01, 2013
 
          Health Management Limited [Member]
 
          GBP (£) 
         | 
        
           Jun. 30, 2014
 
          Health Management Limited [Member]
 
          USD ($) 
         | 
        
           Jul. 01, 2013
 
          Health Management Limited [Member] 
         | 
        
           Jul. 01, 2013
 
          Health Management Limited [Member]
 
          Customer Relationships [Member] 
         | 
        
           Sep. 30, 2013
 
          Health Management Limited [Member]
 
          Scenario, Previously Reported [Member]
 
          USD ($) 
         | 
        
           Jun. 30, 2014
 
          Health Management Limited [Member]
 
          Restatement Adjustment [Member]
 
          USD ($) 
         | 
        
           Jan. 31, 2014
 
          Australia Business [Member]
 
          USD ($) 
         | 
        
           Jan. 31, 2014
 
          Australia Business [Member]
 
          AUD 
         | 
        
           Jan. 31, 2014
 
          Australia Business [Member]
 
          Customer Relationships [Member]
 
          USD ($) 
         | 
      |
| Business combinations | ||||||||||||
| Share capital acquired (as a percent) | 100.00% | |||||||||||
| Preliminary Purchase Price Accounting | ||||||||||||
| Cash consideration, net of cash acquired | $ 2,670,000 | $ 71,400,000 | £ 46,900,000 | $ 71,435,000 | $ 71,435,000 | |||||||
| Stock consideration | 6,400,000 | 4,200,000 | 6,425,000 | 6,425,000 | ||||||||
| Stock consideration (in shares) | 202,972 | 202,972 | ||||||||||
| Purchase consideration, net of cash acquired | 77,900,000 | 51,100,000 | 77,860,000 | 77,860,000 | ||||||||
| Accounts receivable and unbilled receivables | 7,671,000 | 7,671,000 | ||||||||||
| Other current assets | 1,382,000 | 1,382,000 | ||||||||||
| Property and equipment | 2,752,000 | 2,752,000 | ||||||||||
| Intangible assets | 20,542,000 | 20,542,000 | 3,200,000 | |||||||||
| Total identifiable assets acquired | 32,347,000 | 32,347,000 | ||||||||||
| Accounts payable and other liabilities | 6,228,000 | 6,228,000 | ||||||||||
| Deferred revenue | 1,149,000 | 1,149,000 | 500,000 | |||||||||
| Current income tax liability | 756,000 | 612,000 | 144,000 | |||||||||
| Deferred tax liability | 4,701,000 | 4,814,000 | (113,000) | |||||||||
| Total liabilities assumed | 12,834,000 | 12,803,000 | 31,000 | |||||||||
| Net identifiable assets acquired | 19,513,000 | 19,544,000 | (31,000) | |||||||||
| Goodwill | 175,471,000 | 171,867,000 | 58,347,000 | 58,316,000 | 31,000 | |||||||
| Net assets acquired | 77,860,000 | 77,860,000 | ||||||||||
| Cash consideration | $ 2,700,000 | 3,100,000 | ||||||||||
| Amortization period of intangible assets | 19 years 6 months | 19 years 6 months | 20 years | 4 years | ||||||||