Pension and Other Postemployment Benefit Plans (Details) - Pension Benefits [Member] - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Components of net periodic expense of Pension and OPEB plans
Service cost	$ 0.2	$ 0.2	$ 0.4	$ 0.5
Interest cost	1.6	1.9	3.1	3.6
Expected return on plan assets	(2.1)	(2.1)	(4.2)	(4.2)
Amortization of net loss (gain)	0.2	0.1	0.7	0.4
Amortization of unrecognized prior service (credit)	0.0	0.0	0.0	(0.1)
Net periodic expense (benefit)	$ (0.1)	$ 0.1	$ 0.0	$ 0.2