Commitments and Contingencies - Narrative (Details) $ in Millions, $ in Millions	3 Months Ended			12 Months Ended
	Jun. 30, 2018 USD ($)	Mar. 31, 2018 USD ($)	Mar. 31, 2017 USD ($)	Dec. 31, 2017 USD ($)	Sep. 30, 2017 CAD ($)	Sep. 30, 2017 USD ($)	Jun. 30, 2017 USD ($)	Dec. 31, 2016 USD ($)	Jul. 07, 2016 USD ($)
Rochester, New Hampshire
Loss Contingencies [Line Items]
Expense associated with expected costs of site investigation		$ 0.1	$ 0.2
Rochester, New Hampshire | Environmental Contamination
Loss Contingencies [Line Items]
Accrual for environmental liability				$ 0.0
Reduction to accrual for environmental liability, payments				0.2
Accrual for environmental liability, including revision (fully offset)				0.2
Texel | Quebec, Canada
Loss Contingencies [Line Items]
Indemnification assets, minimum estimated outcome									$ 0.9
Indemnification assets, maximum estimated outcome									$ 1.5
Environment remediation indemnity secured by environmental escrow account					$ 3.0	$ 2.3
Environmental remediation indemnity secured by general escrow account					14.0	10.9
Environmental remediation indemnity secured by general escrow account, reduced amount after share purchase agreement					$ 7.0	$ 5.4
Texel | Quebec, Canada | Environmental Contamination
Loss Contingencies [Line Items]
Accrual for environmental liability		0.4						$ 0.9
Accrual for environmental liability, revision of estimate		0.4
Reduction to accrual for environmental liability, payments		$ 0.4		0.7
Accrual for environmental liability, including revision (fully offset)				$ 0.8			$ 1.5
Forecast | Rochester, New Hampshire
Loss Contingencies [Line Items]
Expense associated with expected costs of site investigation	$ 0.2