Selected historical financial information - Consolidated Balance Sheet - Additional Information (Details) - £ / shares |
Mar. 31, 2016 |
Dec. 31, 2015 |
Jun. 30, 2015 |
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| Selected historical financial information | |||
| Common stock, par value | £ 0.001 | £ 0.001 | £ 0.001 |
| X | ||||||||||
- Definition Selected Historical Financial Information [Abstract] No definition available.
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| X | ||||||||||
- Definition Face amount or stated value per share of common stock. Reference 1: http://www.xbrl.org/2003/role/presentationRef
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