Goodwill and Intangible Assets - Additional Information (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Goodwill And Intangible Assets [Line Items]
Fair value assets measured on non-recurring basis	$ 967,933	$ 950,717
Goodwill	660,981	$ 660,981
Accumulated goodwill impairment losses to date	9,300
Fair Value Measurement Non-Recurring | Level 3
Goodwill And Intangible Assets [Line Items]
Fair value assets measured on non-recurring basis	692,600
Goodwill	661,000
Indefinite-lived intangible assets	$ 31,600