Commitments and Contingencies - Narrative (Details) $ in Millions, $ in Millions	3 Months Ended		6 Months Ended	12 Months Ended
	Mar. 31, 2018 USD ($)	Mar. 31, 2017 USD ($)	Jun. 30, 2018 USD ($)	Dec. 31, 2018 USD ($)	Dec. 31, 2017 USD ($)	Sep. 30, 2017 CAD ($)	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]
Reduction to accrual for environmental liability, payments					$ 0.2
Accrual for environmental liability, including revision (fully offset)			$ 0.1		0.2
Accrual for environmental liability					0.0
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			2.3			$ 3.0
Environmental remediation indemnity secured by general escrow account			10.7			14.0
Environmental remediation indemnity secured by general escrow account, reduced amount after share purchase agreement			5.3			$ 7.0
Texel | Quebec, Canada | Environmental Contamination
Loss Contingencies [Line Items]
Reduction to accrual for environmental liability, payments			0.5		0.7
Accrual for environmental liability, including revision (fully offset)			0.4		$ 0.8		$ 1.5
Revision of estimate for environmental liability accrual			(0.5)
Accrual for environmental liability			$ 0.4					$ 0.9
Forecast | Rochester, New Hampshire
Loss Contingencies [Line Items]
Expense associated with expected costs of site investigation				$ 0.2