| Summary of Significant Accounting Policies - Interest income (Details) - USD ($) | 12 Months Ended | ||
|---|---|---|---|
| Dec. 31, 2023 | Dec. 31, 2022 | Dec. 31, 2021 | |
| Summary of Significant Accounting Policies | |||
| (Accretion)/amortization on available-for-sale debt securities | $ (1,986,000) | $ 2,525,000 | $ 5,276,000 | 
| X | ||||||||||
| 
- Definition The amount of Accretion / Amortization for sale debt securities. No definition available. 
 | 
| X | ||||||||||
| 
- References No definition available. 
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