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Goodwill and Intangible Assets - Additional Information (Details) - USD ($)
$ in Millions
3 Months Ended 9 Months Ended
Sep. 30, 2018
Sep. 30, 2017
Sep. 30, 2018
Sep. 30, 2017
Goodwill and Intangible Assets Disclosure [Abstract]        
Amortization expense of intangible assets $ 5.8 $ 6.4 $ 17.8 $ 19.4