Restructuring, Impairment and Other - Schedule of Net Restructuring, Impairment and Other Expenses (Detail) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Restructuring Cost And Reserve [Line Items]
Employee Terminations	$ 2.3	$ 12.8	$ 3.8	$ 20.9
Other Restructuring Charges	7.6	14.0	11.6	18.1
Multi-Employer Pension Plan Charges	0.2	1.2	0.1	1.9
Impairment and Other	(0.4)	0.4		(1.3)
Total	9.7	28.4	15.5	39.6
Total Operating Segments | Business Services
Restructuring Cost And Reserve [Line Items]
Employee Terminations	0.6	6.4	1.4	12.2
Other Restructuring Charges	3.0	1.8	4.6	2.8
Multi-Employer Pension Plan Charges	0.6	1.1	1.2	1.7
Impairment and Other	(0.9)	0.4	(0.5)	(1.3)
Total	3.3	9.7	6.7	15.4
Total Operating Segments | Marketing Solutions
Restructuring Cost And Reserve [Line Items]
Employee Terminations	0.2	1.6	0.5	2.0
Other Restructuring Charges	1.7	0.5	3.5	0.5
Multi-Employer Pension Plan Charges	0.1	0.1	0.2	0.2
Impairment and Other	0.5		0.5
Total	2.5	2.2	4.7	2.7
Corporate
Restructuring Cost And Reserve [Line Items]
Employee Terminations	1.5	4.8	1.9	6.7
Other Restructuring Charges	2.9	11.7	3.5	14.8
Multi-Employer Pension Plan Charges	(0.5)		(1.3)
Total	$ 3.9	$ 16.5	$ 4.1	$ 21.5