| Summary of Significant Accounting Policies - Accounts Receivable (Details) - USD ($) | Mar. 31, 2021 | Dec. 31, 2020 | 
|---|---|---|
| Summary of Significant Accounting Policies | ||
| Customer allowance for prompt payment discounts | $ 105,000 | $ 171,000 | 
| X | ||||||||||
| 
- Definition Amount of customer allowances for prompt payment discounts. No definition available. 
 | 
| X | ||||||||||
| 
- References No definition available. 
 |