Other Expense, Net (Details) - USD ($) $ in Millions		1 Months Ended	12 Months Ended
		Sep. 30, 2015	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Asset disposals and write-offs			$ (10.5)	$ (11.9)	$ (14.0)
Acquisition and integration related costs	[1],[2],[3]		(0.8)	(3.3)	(12.9)
Expiration of timberland repurchase option	[4]		2.0
Hexacomb working capital adjustment	[5]		2.3
Facilities closure and other costs	[6]		5.9	(10.3)
Refundable state tax credit	[7]				3.6
Other			3.9	(1.8)	(2.8)
Total			(18.4)	(24.3)	(6.7)
Wallula, Washington Mill
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Restructuring	[8]		(23.1)
Ceased production of market pulp at Wallula	[9]			$ (0.6)
Deridder Mill
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Restructuring	[10]				7.1
DeRidder mill incident	[11]		$ 9.7
Mill at St. Helens, Oregon
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Sale of St. Helens Paper Mill Site		$ 6.7			$ 6.7	[12]

[1] For 2015, includes Boise acquisition integration-related and other costs, which primarily relate to severance, retention, travel, and professional fees.

[2] For 2016, includes charges related to the acquisition and integration of TimBar Corporation.

[3] For 2017, includes charges related to the Sacramento Container Corporation acquisition and integration costs related to other recent acquisitions.

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

[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] 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. For 2016, includes expenses related to the closure of corrugated products facilities and a paper administration facility and a lump sum settlement of a multiemployer pension plan withdrawal liability for one of our corrugated products facilities.

[7] Includes a tax credit from the State of Louisiana related to capital investment and the jobs retained at the DeRidder, Louisiana mill.

[8] Includes $23.1 million of charges related to our determination to discontinue production of uncoated free sheet and coated one-side grades at the Wallula, Washington mill in the second quarter of 2018 and convert the No. 3 paper machine to a high-performance 100% virgin kraft linerboard machine.

[9] Includes costs related to ceased softwood market pulp operations at our Wallula, Washington mill and the permanent shutdown of the No. 1 machine.

[10] Includes $7.1 million of income from vendor settlements related to our restructuring activities at our DeRidder, Louisiana mill.

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

[12] Includes a gain related to the sale of the remaining land, buildings, and equipment at our paper mill site in St. Helens, Oregon where we ceased paper production in December 2012.