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Stock-Based Compensation - Additional Information (Details) - USD ($)
$ in Millions
3 Months Ended 6 Months Ended
Jun. 30, 2018
Jun. 30, 2017
Jun. 30, 2018
Jun. 30, 2017
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]        
Stock based compensation expense $ 1.4 $ 4.0 $ 6.3 $ 8.7
Stock-based compensation, tax benefits $ 0.3 $ 1.4 $ 1.2 $ 3.0