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Revenue Recognition - Disaggregation of Revenue (Details) - USD ($)
$ in Thousands
3 Months Ended 12 Months Ended
Dec. 31, 2019
Sep. 30, 2019
Jun. 30, 2019
Mar. 31, 2019
Dec. 31, 2018
Sep. 30, 2018
Jun. 30, 2018
Mar. 31, 2018
Dec. 31, 2019
Dec. 31, 2018
Dec. 31, 2017
Disaggregation of Revenue [Line Items]                      
Revenues $ 107,556 $ 108,646 $ 103,542 $ 104,881 $ 104,413 $ 110,630 $ 113,648 $ 105,041 $ 424,625 $ 433,732 $ 402,440
Revenue recognized over time                      
Disaggregation of Revenue [Line Items]                      
Revenues                 16,146 12,943  
Revenue recognized at a point in time                      
Disaggregation of Revenue [Line Items]                      
Revenues                 $ 408,479 $ 420,789