Related party transactions (Details)  | 
3 Months Ended | 
|---|---|
| 
 Mar. 31, 2016  
company 
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| Related Party Transactions [Abstract] | |
| Number of affiliated companies | 2 | 
| X | ||||||||||
- Definition Related Party Transaction, Number of Affiliated Companies No definition available. 
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| X | ||||||||||
- References No definition available. 
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