Restructuring, Impairment and Other - Schedule of Net Restructuring, Impairment and Other Expenses (Detail) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Restructuring Cost And Reserve [Line Items]
Employee Terminations	$ 1.5	$ 8.1
Other Restructuring Charges	4.0	4.1
Multi-Employer Pension Plan Charges	(0.1)	0.7
Impairment and Other	0.4	(1.7)
Total	5.8	11.2
Total Operating Segments | Business Services
Restructuring Cost And Reserve [Line Items]
Employee Terminations	0.8	5.8
Other Restructuring Charges	1.6	1.0
Multi-Employer Pension Plan Charges	0.6	0.6
Impairment and Other	0.4	(1.7)
Total	3.4	5.7
Total Operating Segments | Marketing Solutions
Restructuring Cost And Reserve [Line Items]
Employee Terminations	0.3	0.4
Other Restructuring Charges	1.8
Multi-Employer Pension Plan Charges	0.1	0.1
Total	2.2	0.5
Corporate
Restructuring Cost And Reserve [Line Items]
Employee Terminations	0.4	1.9
Other Restructuring Charges	0.6	3.1
Multi-Employer Pension Plan Charges	(0.8)
Total	$ 0.2	$ 5.0