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Revenues - Schedule Contract Liabilities (Details) - USD ($)
$ in Thousands
9 Months Ended
Sep. 30, 2021
Sep. 30, 2020
Change In Contract With Customer, Liability [Roll Forward]    
Contract liabilities at beginning of period $ 6,738 $ 4,652
Increase 24,745 21,583
Recognized as revenue (22,224) (18,224)
Contract liabilities at end of period $ 9,259 $ 8,011