Other Expense, Net - Components of Other Expense, Net (Details) - USD ($) $ in Millions		3 Months Ended		6 Months Ended
		Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Asset disposals and write-offs		$ (5.0)	$ (4.5)	$ (11.0)	$ (8.8)
Facilities closure and other costs	[1]	(13.3)		(13.7)
Other		0.1	0.7	(3.4)	(0.6)
Total		$ (18.2)	$ (3.8)	$ (28.1)	(9.8)
Wallula, Washington Mill
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Restructuring	[2]				$ (0.4)

[1] Includes charges consisting of closure costs related to corrugated products facilities, substantially all of which relates to the previously announced closure of the San Lorenzo, California facility during the second quarter of 2020, partially offset by income related to the sale of a corrugated products facility.

[2] Includes charges related to the second quarter 2018 discontinuation of uncoated free sheet and coated one-side grades at the Wallula, Washington mill associated with the conversion of the No. 3 paper machine to produce virgin kraft linerboard.