Business and summary of significant accounting policies - Revenue recognition (Details) $ in Millions |
Dec. 31, 2015
USD ($)
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| Organization, Consolidation and Presentation of Financial Statements [Abstract] | |
| Deferred entry fee revenue | $ 1.1 |
| X | ||||||||||
- Definition Deferred Licensing Entry Fee No definition available.
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| X | ||||||||||
- References No definition available.
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