Pension Plans and Other Postretirement Benefit Plans - Narrative (Details) - USD ($) $ in Millions	1 Months Ended	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2016	Dec. 31, 2015	Mar. 31, 2015	Feb. 03, 2016
Pension plans and other postretirement benefit plans
Overfunded defined benefit pension plans	$ 25.5	$ 25.5	$ 26.1
Defined contribution retirement plan
Percentage that the employer contributes of employee contributions under 401(k) plan		100.00%
Maximum percentage of employee compensation match by employer to defined contribution plan		6.00%
Costs related to defined contribution retirement plan		$ 1.1		$ 1.4
Shared Plans
Pension plans and other postretirement benefit plans
Allocated pension expense				0.9
Withdrawal from Multiemployer Defined Benefit Plan
Pension plans and other postretirement benefit plans
Increase to net pension liabilities		44.0	4.0
Postretirement Life Insurance Plans
Pension plans and other postretirement benefit plans
Increase to net pension liabilities		0.1
Allocated income				$ 0.4
Prior service credit assumed as part of acquisition, net of tax					$ 0.8
Actuarial losses, net of tax					$ 0.7
Pension Plans
Pension plans and other postretirement benefit plans
Overfunded defined benefit pension plans	25.5	25.5	26.1
Combined balance of underfunded and unfunded plans included as liabilities	82.0	82.0
Pension liabilities included in other current liabilities	1.2	1.2	1.1
Underfunded and unfunded defined benefit pension plans	80.8	$ 80.8	$ 34.0
U.S.
Pension plans and other postretirement benefit plans
Accelerated contribution to the trusts	$ 1.0