Restructuring, Impairment and Other Charges - Narrative (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Restructuring Cost And Reserve [Line Items]
Employee termination costs	$ 32.8	$ 22.2	$ 12.7
Other restructuring charges	33.8	16.6	15.9
Gain on sale of previously impaired assets	11.8	5.7
Multi-employer pension plan charges	40.0	$ 2.9	3.0
Impairment of other long lived assets			13.7
Long-lived asset implied fair value			0.0
Business Services
Restructuring Cost And Reserve [Line Items]
Gain on sale of previously impaired assets			$ 6.7
LSC Communications, Inc.
Restructuring Cost And Reserve [Line Items]
Multi-employer pension plan, present value of estimated future payments	$ 37.1