Restructuring, Impairment and Other Charges - Additional Information (Details) $ in Millions	12 Months Ended
	Dec. 31, 2017 USD ($) Employee	Dec. 31, 2016 USD ($) Employee	Dec. 31, 2015 USD ($) Employee
Restructuring And Related Activities [Abstract]
Employee termination costs	$ 6.4	$ 3.7	$ 2.3
Number of employees used to determine employee termination costs | Employee	192	84	64
Other restructuring charges	$ 0.3	$ 1.5	$ 1.9
Impairment charges	0.2
Other charges	$ 0.2	$ 0.2	$ 0.2