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Goodwill and Intangible Assets - Additional Information (Details) - USD ($)
$ in Thousands
12 Months Ended
Dec. 31, 2018
Dec. 31, 2017
Dec. 31, 2016
Goodwill And Intangible Assets Disclosure [Abstract]      
Goodwill Impairment Charges $ 0 $ 0 $ 0
Intangible assets impairment charge 0 0 0
Amortization expense $ 15,000 $ 14,400 $ 12,900