Stockholders' Equity - Restricted Stock Units and Restricted Stock Awards - Share-based Compensation Expense (Details) - USD ($) $ in Millions  | 
3 Months Ended | |
|---|---|---|
Mar. 31, 2020  | 
Mar. 31, 2019  | 
|
| Unvested restricted stock units/awards | ||
| Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items] | ||
| Share-based Compensation | $ 0.2 | $ 0.8 | 
| X | ||||||||||
- Definition Amount of expense for award under share-based payment arrangement. Excludes amount capitalized. Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef 
  | 
| X | ||||||||||
- Definition Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table. No definition available. 
  | 
| X | ||||||||||
- Details 
  |