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           Software development costs (Details) (USD $) 
         | 
        12 Months Ended | ||
|---|---|---|---|
| 
           Sep. 30, 2012 
         | 
        
           Sep. 30, 2011 
         | 
        
           Sep. 30, 2010 
         | 
      |
| Software development costs | |||
| Capitalized software development costs | $ 46,767,000 | $ 40,798,000 | |
| Less: Accumulated amortization | (19,377,000) | (14,182,000) | |
| Total Software development costs, net | 27,390,000 | 26,616,000 | |
| Capitalized software amortization expense | $ 4,900,000 | $ 5,500,000 | $ 3,400,000 | 
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- Definition 
          For each balance sheet presented, the amount of accumulated amortization for capitalized computer software costs. Reference 1: http://www.xbrl.org/2003/role/presentationRef 
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- Definition 
          For each income statement presented, the amount charged to expense for amortization of capitalized computer software costs. Reference 1: http://www.xbrl.org/2003/role/presentationRef 
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- Definition 
          The gross amount of capitalized computer software costs as of the balance sheet date. Reference 1: http://www.xbrl.org/2003/role/presentationRef 
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- Definition 
          The carrying amount of capitalized computer software costs net of accumulated amortization as of the balance sheet date. Reference 1: http://www.xbrl.org/2003/role/presentationRef 
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- Details 
          
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