Summary of Significant Accounting Policies (Details) - USD ($) |
36 Months Ended | |
|---|---|---|
Dec. 31, 2018 |
Dec. 31, 2017 |
|
| Summary of Significant Accounting Policies | ||
| Restricted cash for the benefit of the landlords of leased properties | $ 1,800,000 | $ 300,000 |
| Restricted cash to collateralize corporate credit card | 500,000 | |
| Restricted cash (non-current) | 1,735,000 | $ 284,000 |
| Restricted cash (current) | 622,000 | |
| Other than Temporary Impairment Losses, Investments | $ 0 |