Stockholders' Equity - Narrative - Restricted Stock (Details) |
12 Months Ended |
|---|---|
Dec. 31, 2017 | |
| RSU [Member] | |
| Share-based Compensation Arrangement by Share-based Payment Award [Line Items] | |
| Vesting period | 4 years |
| PSU [Member] | |
| Share-based Compensation Arrangement by Share-based Payment Award [Line Items] | |
| Vesting period | 3 years |
| PSU [Member] | Maximum [Member] | |
| Share-based Compensation Arrangement by Share-based Payment Award [Line Items] | |
| Vesting percent | 150.00% |