Annual report pursuant to Section 13 and 15(d)

Stock-Based Compensation - Summary of Stock Option Exercises (Details)

v3.8.0.1
Stock-Based Compensation - Summary of Stock Option Exercises (Details) - USD ($)
$ in Millions
12 Months Ended
Dec. 31, 2017
Dec. 31, 2016
Dec. 31, 2015
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]      
Total intrinsic value of stock options exercised $ 0.5 $ 0.2  
Cash proceeds received from options exercised $ 1.4 $ 0.3 $ 0.0