Goodwill and Intangible Assets - Goodwill (Details) - USD ($)		3 Months Ended	12 Months Ended
		Dec. 31, 2021	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Goodwill [Line Items]
Beginning Balance			$ 863,500,000	$ 918,700,000
Impairment of Paper segment		$ 0	0	(55,200,000)	$ 0
Ending Balance		923,500,000	923,500,000	863,500,000	918,700,000
Advance Packaging Corporation [Member]
Goodwill [Line Items]
Acquisitions	[1]		60,000,000.0
Ending Balance		60,000,000.0	60,000,000.0
Packaging
Goodwill [Line Items]
Beginning Balance			863,500,000	863,500,000
Ending Balance		923,500,000	923,500,000	863,500,000	863,500,000
Packaging | Advance Packaging Corporation [Member]
Goodwill [Line Items]
Acquisitions	[1]		60,000,000.0
Paper
Goodwill [Line Items]
Beginning Balance			0	55,200,000
Impairment of Paper segment				(55,200,000)
Ending Balance		$ 0	0	$ 0	$ 55,200,000
Paper | Advance Packaging Corporation [Member]
Goodwill [Line Items]
Acquisitions	[1]		$ 0

[1] In connection with the December 2021 acquisition of Advance Packaging, the Company recorded $60.0 million of goodwill in the Packaging segment.