Acquisitions - Purchase Price Allocation (Details) - USD ($) $ in Millions	Jun. 01, 2017	Sep. 30, 2018	Dec. 31, 2017
Business Acquisition [Line Items]
Goodwill		$ 1,248.0	$ 1,271.2
Industrial Wood Acquisition [Member]
Business Acquisition [Line Items]
Accounts and notes receivable—trade	$ 23.3
Inventories	24.7
Prepaid expenses and other	0.2
Property, plant and equipment	23.1
Identifiable intangibles	259.1
Accounts payable	(22.2)
Other accrued liabilities	(4.7)
Net assets acquired before goodwill on acquisition	303.5
Goodwill	126.8
Net assets acquired	430.3
Measurement Period Adjustments
Accounts and notes receivable—trade	0.0
Inventories	(0.2)
Prepaid expenses and other	0.0
Property, plant and equipment	0.1
Identifiable intangibles	4.9
Accounts payable	0.2
Other accrued liabilities	0.4
Net assets acquired before goodwill on acquisition	5.4
Goodwill on acquisition	(5.8)
Net assets acquired	(0.4)
Scenario, Previously Reported [Member] | Industrial Wood Acquisition [Member]
Business Acquisition [Line Items]
Accounts and notes receivable—trade	23.3
Inventories	24.9
Prepaid expenses and other	0.2
Property, plant and equipment	23.0
Identifiable intangibles	254.2
Accounts payable	(22.4)
Other accrued liabilities	(5.1)
Net assets acquired before goodwill on acquisition	298.1
Goodwill	132.6
Net assets acquired	$ 430.7