| Summary of Significant Accounting Policies - Retirement Benefits (Details) - USD ($) | 12 Months Ended | ||
|---|---|---|---|
| Dec. 31, 2022 | Dec. 31, 2021 | Dec. 31, 2020 | |
| Summary of Significant Accounting Policies | |||
| Pension contributions | $ 2,810,000 | $ 2,505,000 | $ 2,070,700 | 
| X | ||||||||||
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- References No definition available. 
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| X | ||||||||||
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- Definition Amount of cost for defined contribution plan. Reference 1: http://www.xbrl.org/2003/role/disclosureRef 
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