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Fair Value Measurement - Change in Fair Value Of Liability (Details) - Long-term Debt - Phantom Stock Appreciation Rights (PSARs)
$ in Thousands
3 Months Ended
Mar. 31, 2021
USD ($)
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]  
Balance at December 31, 2020 $ 858
Change in fair value 215
Balance at March 31, 2021 $ 1,073