Other Income (Expense), Net - Components of Other Income (Expense), Net (Details) - USD ($) $ in Millions		3 Months Ended		6 Months Ended
		Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Asset disposals and write-offs		$ (4.5)	$ (4.1)	$ (8.8)	$ (9.2)
Facilities closure and other costs	[1]				(0.1)
Other		0.7	(2.0)	(0.6)	(4.4)
Total		$ (3.8)	(13.3)	(9.8)	(21.6)
Wallula, Washington Mill
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Restructuring	[2]		$ (7.2)	$ (0.4)	$ (7.9)

[1] Includes charges consisting of closure costs related to corrugated products facilities.

[2] Includes charges related to the discontinuation of production of uncoated free sheet and coated one-side grades at the Wallula, Washington mill in the second quarter of 2018 and the conversion of the No. 3 paper machine to a high-performance 100% virgin kraft linerboard machine.