Summary of significant accounting policies - Short-Term Investments (Details) |
12 Months Ended |
|---|---|
Dec. 31, 2015 | |
| Accounting Policies [Abstract] | |
| Short-Term Investments, Minimum Maturity Term | 3 months |
| Short-Term Investments, Maximum Maturity Term | 1 year |
| X | ||||||||||
- Definition Short-Term Investments, Maximum Maturity Term No definition available.
|
| X | ||||||||||
- Definition Short-Term Investments, Minimum Maturity Term No definition available.
|
| X | ||||||||||
- References No definition available.
|