Stockholders' Equity - Schedule of Assumptions used for Fair Value of Warrants (Details) |
12 Months Ended | ||
|---|---|---|---|
Dec. 31, 2015 |
Dec. 31, 2014 |
Dec. 31, 2013 |
|
| Class of Stock [Line Items] | |||
| Contractual life | 6 years 11 days | 6 years 2 months 27 days | 6 years 22 days |
| Dividend yield | 0.00% | 0.00% | 0.00% |
| USAA | Common Stock Purchase Warrants | |||
| Class of Stock [Line Items] | |||
| Minimum risk-free interest rate | 1.51% | 0.02% | 0.29% |
| Maximum risk-free interest rate | 2.03% | 2.33% | 0.52% |
| Minimum expected volatility | 47.80% | 48.50% | 47.40% |
| Maximum expected volatility | 54.20% | 57.50% | 52.80% |
| Dividend yield | 0.00% | 0.00% | 0.00% |
| USAA | Common Stock Purchase Warrants | Minimum | |||
| Class of Stock [Line Items] | |||
| Contractual life | 6 years 3 months 18 days | 3 months 18 days | 2 years |
| USAA | Common Stock Purchase Warrants | Maximum | |||
| Class of Stock [Line Items] | |||
| Contractual life | 7 years 2 months 12 days | 8 years | 2 years 10 months 24 days |