Pension and Post-retirement Plans - Summary of Components of Net Periodic Benefit Cost (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Pension Benefits
Components of net periodic benefit cost [Abstract]
Service cost	$ 0.8	$ 0.7	$ 2.3	$ 1.9
Interest cost	2.0	2.1	6.0	6.2
Expected return on plan assets	(2.8)	(2.7)	(8.3)	(8.0)
Amortization of prior service credit	(0.2)	(0.2)	(0.6)	(0.6)
Amortization of net loss	1.0	1.0	4.5	3.0
Net periodic benefit cost	0.8	0.9	3.9	2.5
Post-retirement Benefits
Components of net periodic benefit cost [Abstract]
Service cost	0.0	0.0	0.1	0.1
Interest cost	0.1	0.2	0.3	0.4
Expected return on plan assets	0.0	0.0	0.0	0.0
Amortization of prior service credit	0.0	0.0	0.0	0.0
Amortization of net loss	0.0	0.1	0.1	0.2
Net periodic benefit cost	$ 0.1	$ 0.3	$ 0.5	$ 0.7