Pension Plans and Other Postretirement Benefit Plans - Net Funded Status of Over-Funded, Underfunded, and Unfunded Pension Plans (Details) - USD ($) $ in Millions	Jun. 30, 2016	Dec. 31, 2015
Pension plans and other postretirement benefit plans
Overfunded defined benefit pension plans	$ 24.4	$ 26.1
Underfunded defined benefit pension plans	(80.9)	(34.0)
Pension Plans
Pension plans and other postretirement benefit plans
Overfunded defined benefit pension plans	24.4	26.1
Underfunded defined benefit pension plans	(46.0)	(8.0)
Unfunded defined benefit pension plans	(34.9)	(26.0)
Total underfunded and unfunded defined benefit pension plans	(80.9)	(34.0)
Pension liabilities included in other current liabilities	(1.2)	(1.1)
Net funded status	$ (57.7)	$ (9.0)