Other Expense, Net - Components Expense, Net (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2014		Dec. 31, 2013		Dec. 31, 2012
Other Income and Expenses [Abstract]
Integration-related and other costs	$ 20.0	[1]	$ 17.4	[1]	$ 0
Class action lawsuit settlement	17.6	[2]	0		0
DeRidder restructuring	7.3	[3]	0		0
Pension curtailment charges	0		10.9	[4]	0
Acquisition-related costs	0		17.2	[5]	0
Asset disposals and write-offs	10.1		13.2		10.8
Other	2.3		0.3		1.0
Total	$ 57.3		$ 59.0		$ 11.8

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

[2] Includes $17.6 million of costs for the settlement of the Kleen Products LLC v Packaging Corp. of America et al class action lawsuit. See Note 20, Commitments, Guarantees, Indemnifications, and Legal Proceedings, for more information.

[3] Costs relate primarily to the conversion of the No. 3 newsprint machine at our DeRidder, Louisiana, mill to produce lightweight linerboard and corrugating medium, and our exit from the newsprint business in September 2014.

[4] Includes $10.9 million of non-cash pension curtailment charges related to pension plan changes in which certain hourly corrugated plant and containerboard mill employees will transition from a defined benefit pension plan to a defined contribution (401k) plan.

[5] Includes $17.2 million of acquisition-related costs, primarily for professional fees related to transaction-advisory services and expenses related to financing the acquisition of Boise.