Commitments and Contingencies - Narrative (Detail) $ in Millions	3 Months Ended	12 Months Ended
	Dec. 31, 2020 USD ($) Facility	Dec. 31, 2020 USD ($) Facility	Apr. 13, 2020 USD ($)
Commitment And Contingencies [Line Items]
Number of sites cited as potentially responsible party | Facility	2	2
Number of previously and currently owned sites with potential remediation obligations | Facility	6	6
Donnelley Financial Solutions, Inc.
Commitment And Contingencies [Line Items]
Potential contingent lease obligations	$ 2.8	$ 2.8
LSC Communications, Inc.
Commitment And Contingencies [Line Items]
Potential contingent lease obligations	49.4	49.4
Multi-employer pension plan obligation	100.0	$ 100.0
Multi-employer pension plan obligation payment period		13 years
Multi-employer pension plan, present value of estimated future payments	37.1	$ 37.1
Claim and other claims settled from general unsecured creditors	$ 5.5
The Buyer
Commitment And Contingencies [Line Items]
Future lease obligations not assumed			$ 3.0