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Summary of Significant Accounting Policies Significant Accounting Policies (Details) - USD ($) $ in Thousands | 3 Months Ended | 9 Months Ended |
--- | --- | --- | ---
Sep. 30, 2023 | Sep. 30, 2022 | Sep. 30, 2023 | Sep. 30, 2022 | Dec. 31, 2022
Accounting Policies [Abstract] |  |  |  |  |
Treasury money market funds, at fair value | $ 149,700 |  | $ 149,700 |  | $ 168,100
Equity Investments | 7,200 |  | 7,200 |  | 7,100
Gain (Loss) on Investments | 0 | $ 3,308 | 0 | $ 3,308 |
Deferred Costs | 14,100 |  | 14,100 |  | 14,800
Amortization of Deferred Charges | 1,400 | 1,500 | 4,400 | 4,300 |
Capitalized Contract Cost, Net | 1,100 |  | 1,100 |  | $ 1,600
Capitalized Contract Cost, Amortization | 200 | 300 | 600 | 900 |
Asset Impairment Charges | $ 0 | $ 0 | $ 0 | $ 1,551 |

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