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Goodwill and Intangible Assets - Narrative (Details) - USD ($)
 12 Months Ended
Dec. 31, 2017
Dec. 31, 2016
Dec. 31, 2015
Finite-Lived Intangible Assets [Line Items]      
Goodwill impairment $ 0 $ 0  
Indefinite-lived intangible asset impairment   0  
Amortization of intangible assets 4,700,000 5,100,000 $ 37,600,000
Amortizable intangible assets, net carrying value 17,900,000 $ 37,900,000  
Internally developed software      
Finite-Lived Intangible Assets [Line Items]      
Amortizable intangible assets, net carrying value 12,500,000    
Intangible Assets, Excluding Internally Developed Software Yet To Be Placed Into Service      
Finite-Lived Intangible Assets [Line Items]      
2018 4,100,000    
2019 3,200,000    
2020 2,900,000    
2021 2,000,000    
2022 300,000    
Thereafter 0    
Amortizable intangible assets, net carrying value $ 12,500,000