Components of Net Periodic Benefit Cost (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Pension Costs
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 0.3	$ 0.9	$ 1.1
Interest cost	2.9	4.2	4.0
Expected return on plan assets	(4.8)	(6.1)	(4.2)
Amortization of prior service cost	0.0	0.0	0.0
Settlements/curtailments	9.6	0.3	0.0
Recognized actuarial loss (gain)	0.2	0.4	0.9
Net periodic benefit cost	8.2	(0.3)	1.8
Nonpension Postretirement Costs
Defined Benefit Plan Disclosure [Line Items]
Service cost	0.2	0.2	0.4
Interest cost	0.9	1.0	1.1
Expected return on plan assets	0.0	0.0	0.0
Amortization of prior service cost	(0.7)	(1.4)	(0.8)
Settlements/curtailments	0.0	0.0	(0.3)
Recognized actuarial loss (gain)	0.1	0.0	0.1
Net periodic benefit cost	$ 0.5	$ (0.2)	$ 0.5