Stockholders' Equity - Reclassifications Out of Accumulated Other Comprehensive Income (Details) - USD ($) $ in Millions	3 Months Ended															12 Months Ended
	Dec. 31, 2015	[4]	Sep. 30, 2015	[5]	Jun. 30, 2015	[6]	Mar. 31, 2015	[7]	Dec. 31, 2014	Sep. 30, 2014	[8]	Jun. 30, 2014	[9]	Mar. 31, 2014	[10]	Dec. 31, 2015	Dec. 31, 2014		Dec. 31, 2013
Reclassification Adjustment out of Accumulated Other Comprehensive Income on Derivatives [Line Items]
Interest expense, net																$ (85.5)	$ (88.4)	[1]	$ (58.3)	[2],[3]
Income before taxes																664.5	614.3		423.6	[3]
(Provision) benefit for income taxes																(227.7)	(221.7)		17.7
Net income	$ 104.3		$ 127.8		$ 114.0		$ 90.8		$ 98.5	$ 104.4		$ 99.6		$ 90.1		436.8	392.6		$ 441.3
Unfunded Employee Benefit Obligations | Reclassification Out Of Accumulated Other Comprehensive Income
Reclassification Adjustment out of Accumulated Other Comprehensive Income on Derivatives [Line Items]
Amortization of prior service cost																(5.6)	(6.3)
Amortization of actuarial gain / (losses)																(8.8)	(0.7)
Income before taxes																(14.4)	(7.0)
(Provision) benefit for income taxes																5.6	2.8
Net income																(8.8)	(4.2)
Foreign Exchange Contract | Foreign Currency Translation Adjustments | Reclassification Out Of Accumulated Other Comprehensive Income
Reclassification Adjustment out of Accumulated Other Comprehensive Income on Derivatives [Line Items]
Interest expense, net																(4.2)	0.0
(Provision) benefit for income taxes																0.0	0.0
Net income																(4.2)	0.0
Treasury Lock | Accumulated Net Gain (Loss) from Designated or Qualifying Cash Flow Hedges | Reclassification Out Of Accumulated Other Comprehensive Income
Reclassification Adjustment out of Accumulated Other Comprehensive Income on Derivatives [Line Items]
Interest expense, net																(5.7)	(5.7)
(Provision) benefit for income taxes																2.2	2.2
Net income																$ (3.5)	$ (3.5)

[1] Includes $1.5 million of expense related to the write-off of deferred financing costs in connection with the debt refinancing discussed in Note 10, Debt.

[2] Includes $10.5 million of expenses for financing the Boise acquisition and $1.1 million of expense for the write-off of deferred financing costs.

[3] On October 25, 2013, we acquired Boise Inc. (Boise). Our financial results include Boise subsequent to acquisition.

[4] Includes $3.5 million of income from DeRidder restructuring ($2.2 million after-tax or $0.02 per diluted share) and $3.8 million of integration-related and other costs ($2.6 million after-tax or $0.03 per diluted share).

[5] Includes $3.8 million of income from DeRidder restructuring ($2.3 million after-tax or $0.02 per diluted share) and $2.4 million of integration-related and other costs ($1.7 million after-tax or $0.02 per diluted share). Also includes $6.7 million gain from the sale of our paper mill site at St. Helens, Oregon ($4.4 million after tax or $0.05 per diluted share).

[6] Includes $1.0 million of income from DeRidder restructuring ($0.7 million after-tax or $0.01 per diluted share) and $3.7 million of integration-related and other costs ($2.3 million after-tax or $0.03 per diluted share). Gross profit has been revised to correct an error in the previous presentation totaling $6.0 million reclassified from "Selling, general, and administrative expenses" to "Cost of Sales" for the three months ended June 30, 2015.

[7] Includes $10.3 million of DeRidder restructuring charges ($6.6 million after-tax or $0.07 per diluted share) and $3.5 million of integration-related and other costs ($2.2 million after-tax or $0.02 per diluted share). Also includes a $3.6 million tax credit from the State of Louisiana related to our recent capital investment and the jobs retained at the DeRidder, Louisiana mill.

[8] Includes $26.0 million of DeRidder restructuring charges ($16.6 million after-tax or $0.17 per diluted share) and $4.5 million of integration-related and other costs ($2.9 million after-tax or $0.03 per diluted share).

[9] Includes $17.8 million of DeRidder restructuring charges ($11.2 million after-tax or $0.12 per diluted share) and $4.9 million of integration-related and other costs ($3.0 million after-tax or $0.03 per diluted share).

[10] Includes $17.6 million of costs accrued for the settlement of the Kleen Products LLC v Packaging Corp. of America et al class action lawsuit ($11.2 million after-tax or $0.11 per diluted share), $4.1 million of integration-related costs ($2.6 million after-tax or $0.03 per diluted share), and $4.0 million of DeRidder restructuring charges ($2.6 million after-tax or $0.02 per diluted share).