Stockholders' Equity - Warrants (Details) - $ / shares |
Mar. 31, 2018 |
Dec. 31, 2017 |
---|---|---|
Class of Stock [Line Items] | ||
Exercise price per share (in USD per share) | $ 14.95 | $ 14.95 |
Common Stock | ||
Class of Stock [Line Items] | ||
Shares available for purchase under common stock warrants (in shares) | 34,113 | 34,113 |