Summary of Significant Accounting Policies - Property, Equipment and Software (Details) |
12 Months Ended |
|---|---|
Dec. 31, 2015 | |
| Capitalized internal-use software costs | |
| Property, Plant and Equipment [Line Items] | |
| Estimated useful life of property, equipment and software | 3 years |
| Furniture and office equipment | |
| Property, Plant and Equipment [Line Items] | |
| Estimated useful life of property, equipment and software | 3 years |
| Furniture and office equipment | |
| Property, Plant and Equipment [Line Items] | |
| Estimated useful life of property, equipment and software | 3 years |