Employee Benefit Plans - Net Periodic Benefit Cost (Details) - Defined benefit pension plans - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Components of net periodic pension benefit cost:
Service cost	$ 2.2	$ 2.5	$ 2.2
Interest cost	4.1	4.3	4.9
Expected return on plan assets	(5.8)	(5.9)	(6.6)
Amortization of actuarial losses	0.3	1.1	0.5
Net periodic cost	$ 0.8	$ 2.0	$ 1.0