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           Business combinations (Details 2) 
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        6 Months Ended | 0 Months Ended | 
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           Mar. 31, 2015 
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           Apr. 01, 2015 
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| Intangible assets acquired | ||
| Useful life | 11 years 6 months | |
| Technology-based intangible assets | ||
| Intangible assets acquired | ||
| Useful life | 2 years 10 months 24 days | |
| Acentia LLC | Customer relationships | Subsequent events | ||
| Intangible assets acquired | ||
| Amortization period of intangible assets | 14 years | 
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- Definition 
          Weighted average amortization period of finite-lived intangible assets acquired either individually or as part of a group of assets, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days. Reference 1: http://www.xbrl.org/2003/role/presentationRef 
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- Definition 
          Useful life of finite-lived intangible assets, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days. No definition available. 
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