Employee Benefit Plans - Components of Net Periodic Benefit Expense (Details) - German - Defined Benefit Pension Plan - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 0.2	$ 0.2	$ 0.5	$ 0.4
Interest cost	0.2	0.3	0.4	0.5
Amortization of net actuarial gains				(0.1)
Expected return on plan assets		(0.1)		(0.1)
Net periodic benefit expense	$ 0.4	$ 0.4	$ 0.9	$ 0.7