Nature of Business and Summary of Significant Accounting Policies - Goodwill (Details) - USD ($)	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014
Goodwill [Roll Forward]
Goodwill, beginning balance	$ 1,118,100,000	$ 1,125,400,000
Disposal of Business		(55,400,000)
Acquisition of Businesses	55,600,000	51,900,000
Foreign Currency Effects	(5,900,000)	(3,800,000)
Goodwill, ending balance	1,167,800,000	1,118,100,000
Paperboard Mills
Goodwill [Roll Forward]
Goodwill, beginning balance	408,500,000	408,500,000
Disposal of Business		0
Acquisition of Businesses	0	0
Foreign Currency Effects	0	0
Goodwill, ending balance	408,500,000	408,500,000
Americas Paperboard Packaging
Goodwill [Roll Forward]
Goodwill, beginning balance	644,100,000	692,500,000
Disposal of Business		(47,200,000.0)
Acquisition of Businesses	55,600,000.0	0
Foreign Currency Effects	(1,400,000.0)	(1,200,000.0)
Goodwill, ending balance	698,300,000	644,100,000
Europe Paperboard Packaging
Goodwill [Roll Forward]
Goodwill, beginning balance	65,500,000	16,200,000
Disposal of Business		0
Acquisition of Businesses	0	51,900,000
Foreign Currency Effects	(4,500,000)	(2,600,000)
Goodwill, ending balance	61,000,000	65,500,000
Flexible Packaging
Goodwill [Roll Forward]
Goodwill, beginning balance	0	8,200,000
Disposal of Business		(8,200,000)
Acquisition of Businesses	0	0
Foreign Currency Effects	0	0
Goodwill, ending balance	$ 0	$ 0