Pension Plans and Other Postretirement Benefit Plans - Pension Plans and Other Postretirement Benefit (Details) - USD ($) $ in Millions	Jun. 30, 2017	Dec. 31, 2016
Funded status of fully funded, underfunded, and unfunded pension plans:
Underfunded and unfunded defined benefit pension plans	$ 444.2	$ 424.3
Pension liabilities included in other current liabilities	15.0	14.4
Net funded status	(459.2)	(438.7)
Underfunded defined benefit pension plans [Member]
Funded status of fully funded, underfunded, and unfunded pension plans:
Underfunded and unfunded defined benefit pension plans	81.5	83.1
Unfunded defined benefit pension plans [Member]
Funded status of fully funded, underfunded, and unfunded pension plans:
Underfunded and unfunded defined benefit pension plans	$ 362.7	$ 341.2