Segment Information (Details) $ in Millions		3 Months Ended				6 Months Ended
		Jun. 30, 2016 USD ($)		Jun. 30, 2015 USD ($)		Jun. 30, 2016 USD ($)		Jun. 30, 2015 USD ($)
Segment Reporting Information [Line Items]
Number of reportable segments						3
Facilities closure costs and other	[1]	$ 1.4		$ 0.0		$ 3.3		$ 0.0
Integration-related and other costs	[2]	0.0		3.6		0.0		6.7
Trade sales		1,417.4		1,454.3		2,818.4		2,880.0
Net sales		1,417.4		1,454.3		2,818.4		2,880.0
Operating income (loss)		200.2		197.6		381.0		354.7
Interest expense, net		(22.5)		(22.2)		(44.1)		(41.4)
Income before taxes		177.7		175.4		336.9		313.3
Acquisition-related costs	[3]	0.3		0.0		0.3		0.0
Costs related to withdrawal from multiemployer pension plan	[4]	0.9		0.0		0.9		0.0
Packaging
Segment Reporting Information [Line Items]
Trade sales		1,123.6		1,140.9		2,217.4		2,238.8
Operating income (loss)		192.4	[5]	194.6	[6]	353.9	[5]	335.7	[6]
Paper
Segment Reporting Information [Line Items]
Trade sales		266.8		281.1		547.3		578.4
Operating income (loss)		24.4	[5]	23.4		60.5	[5]	59.0
Corporate and Other
Segment Reporting Information [Line Items]
Trade sales		27.0		32.3		53.7		62.8
Operating income (loss)		(16.6)		(20.4)	[7]	(33.4)		(40.0)	[7]
Intersegment Eliminations
Segment Reporting Information [Line Items]
Intersegment sales		0.0		0.0		0.0		0.0
Intersegment Eliminations | Packaging
Segment Reporting Information [Line Items]
Intersegment sales		1.7		1.3		3.4		2.7
Intersegment Eliminations | Paper
Segment Reporting Information [Line Items]
Intersegment sales		0.0		0.0		0.0		0.0
Intersegment Eliminations | Corporate and Other
Segment Reporting Information [Line Items]
Intersegment sales		33.0		34.1		69.0		64.6
Operating Segments
Segment Reporting Information [Line Items]
Net sales		1,417.4		1,454.3		2,818.4		2,880.0
Operating Segments | Packaging
Segment Reporting Information [Line Items]
Net sales		1,125.3		1,142.2		2,220.8		2,241.5
Operating Segments | Paper
Segment Reporting Information [Line Items]
Net sales		266.8		281.1		547.3		578.4
Operating Segments | Corporate and Other
Segment Reporting Information [Line Items]
Net sales		60.0		66.4		122.7		127.4
Segment Reconciling Items
Segment Reporting Information [Line Items]
Intersegment sales		(34.7)		(35.4)		(72.4)		(67.3)
Net sales		(34.7)		(35.4)		(72.4)		(67.3)
Other Expense and Cost of Sales
Segment Reporting Information [Line Items]
Facilities closure costs and other		1.7				$ 4.5
Other Expense and Cost of Sales | Restructuring Charges
Segment Reporting Information [Line Items]
Operating income (loss)				1.0				(9.3)
Other Expense, Net
Segment Reporting Information [Line Items]
Costs related to withdrawal from multiemployer pension plan	[4]	0.9
Other Expense, Net | Integration-Related and Other Costs
Segment Reporting Information [Line Items]
Integration-related and other costs				2.0				4.6
TimBar Corporation | Other Expense, Net
Segment Reporting Information [Line Items]
Acquisition-related costs		$ 0.3
Boise Acquisition | Other Expense, Net | Integration-Related and Other Costs
Segment Reporting Information [Line Items]
Integration-related and other costs				$ 1.7				$ 2.6

[1] The three and six months ended June 30, 2016 include facilities closure costs related to corrugated products facilities and a paper products facility.

[2] The three and six months ended June 30, 2015 include Boise acquisition integration-related and other costs. These costs primarily relate to professional fees, severance, retention, relocation, travel, and other integration-related costs.

[3] The three and six months ended June 30, 2016 include acquisition-related costs for the announced TimBar Corporation acquisition.

[4] The three and six months ended June 30, 2016 include costs related to our withdrawal from a multiemployer pension plan for one of our corrugated products facilities.

[5] The three and six months ended June 30, 2016 include $1.7 million and $4.5 million, respectively, of closure costs related to corrugated products facilities and a paper products facility. The closure costs are recorded within "Other expense, net" and "Cost of sales", as appropriate.

[6] The three and six months ended June 30, 2015 include $1.0 million of income and $9.3 million of expense, respectively, related to restructuring charges at our mill in DeRidder, Louisiana, which were recorded in "Other expense, net" and "Cost of sales", as appropriate.The three and six months ended June 30, 2015 include $1.7 million and $2.6 million of Boise acquisition integration-related and other costs, respectively. These costs primarily relate to professional fees, severance, retention, relocation, travel, and other integration-related costs, and are mostly recorded in "Other expense, net".

[7] The three and six months ended June 30, 2015 include $2.0 million and $4.6 million, respectively, of Boise acquisition integration-related and other costs, mostly recorded in "Other expense, net". Boise acquisition integration-related and other costs, primarily recorded in "Other expense, net".