Restructuring, Impairment and Other Charges - Schedule of Net Restructuring, Impairment and Other Charges (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Restructuring Cost And Reserve [Line Items]
Employee Terminations	$ 32.8	$ 22.2	$ 12.7
Other Restructuring Charges	33.8	16.6	15.9
Impairment and Other	(6.6)	(5.0)	7.0
Multi-Employer Pension Plan Charges	40.0	2.9	3.0
Total	100.0	36.7	38.6
Total Operating Segments | Business Services
Restructuring Cost And Reserve [Line Items]
Employee Terminations	18.0	20.1	9.9
Other Restructuring Charges	8.7	7.4	8.3
Impairment and Other	(7.8)	(5.0)	4.8
Multi-Employer Pension Plan Charges	2.5	2.5	2.6
Total	21.4	25.0	25.6
Total Operating Segments | Marketing Solutions
Restructuring Cost And Reserve [Line Items]
Employee Terminations	4.6	0.5	2.0
Other Restructuring Charges	3.7	0.1
Impairment and Other	1.2		1.5
Multi-Employer Pension Plan Charges	0.4	0.4	0.4
Total	9.9	1.0	3.9
Corporate
Restructuring Cost And Reserve [Line Items]
Employee Terminations	10.2	1.6	0.8
Other Restructuring Charges	21.4	9.1	7.6
Impairment and Other			0.7
Multi-Employer Pension Plan Charges	37.1
Total	$ 68.7	$ 10.7	$ 9.1