Employee Benefits - Additional Information (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Defined Benefit Plan Disclosure [Line Items]
Employee 401(K) profit sharing plan, maximum annual matching per employee	6.00%
Employee 401(K) profit sharing plan, employer matching contribution	50.00%
Defined Contribution Plan, Cost Recognized	$ 0.0	$ 2.0	$ 3.0
Europe [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Contribution Plan, Cost Recognized	$ 0.2	$ 0.1	$ 0.2