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Summary of significant accounting policies (Details)
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3 Months Ended |
|---|---|
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Mar. 31, 2015
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| Buildings [Member] | |
| Property, Plant and Equipment [Line Items] | |
| Property, Plant and Equipment, Useful Life | 20 years |
| Machinery and equipment [Member] | |
| Property, Plant and Equipment [Line Items] | |
| Property, Plant and Equipment, Useful Life | 10 years |
| Furniture and fixtures [Member] | |
| Property, Plant and Equipment [Line Items] | |
| Property, Plant and Equipment, Useful Life | 10 years |
| Office equipment and software [Member] | |
| Property, Plant and Equipment [Line Items] | |
| Property, Plant and Equipment, Useful Life | 5 years |
| Vehicles [Member] | |
| Property, Plant and Equipment [Line Items] | |
| Property, Plant and Equipment, Useful Life | 5 years |