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Revenue - Contract Liabilities (Details) - USD ($)
$ in Thousands
Sep. 26, 2021
Dec. 31, 2020
Sep. 27, 2020
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Roll Forward]      
Balance, beginning of period $ 36,614 $ 31,209 $ 29,745
Balance, end of period $ 38,682 $ 36,614 $ 31,209