Other (Expense) Income, Net - Components of Other (Expense) Income, Net (Details) - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Asset disposals and write-offs	[1]	$ (25.0)	$ (17.3)	$ (10.5)
Facilities closure and other costs	[2]	(0.3)	(1.6)	5.9
Insurance deductible for property damage	[3]		(0.5)
Acquisition and integration related costs	[4]		(0.2)	(0.8)
Hexacomb working capital adjustment	[5]			2.3
Expiration of timberland repurchase option	[6]			2.0
Other		(6.7)	(6.7)	(3.9)
Total		(32.7)	(41.2)	(18.4)
Wallula, Washington Mill
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Restructuring	[7]	$ (0.7)	$ (14.9)	(23.1)
DeRidder, Louisiana Mill
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
DeRidder mill incident	[8]			$ 9.7

[1] For 2019, includes $3.0 million of charges for the disposal of fixed assets related to the containerboard mill conversion at our DeRidder, Louisiana mill.

[2] For 2019, includes charges consisting of closure costs related to corrugated products facilities, partially offset by income from the sale of a building related to a closed corrugated products facility. For 2018, includes charges consisting of closure costs related to corrugated products facilities. For 2017, includes income primarily related to the sale of land corresponding to the closure of a corrugated products facility, partially offset by closure costs related to corrugated products facilities, a paper administration facility, a corporate administration facility, and a lump sum settlement of a multiemployer pension plan withdrawal liability for one of our corrugated products facilities.

[3] Includes charges for the property damage insurance deductible for a weather-related incident at one of our corrugated products facilities.

[4] Includes charges for acquisition and integration costs related to recent acquisitions.

[5] Includes income related to a working capital adjustment from the April 2015 sale of our Hexacomb corrugated manufacturing operations in Europe and Mexico.

[6] Includes a gain related to the expiration of a repurchase option corresponding to timberland previously sold.

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

[8] Includes the property damage and business interruption insurance recoveries and corresponding costs related to the February 2017 explosion at our DeRidder, Louisiana mill.