Restructuring, Impairment and Other - Schedule of Net Restructuring, Impairment and Other Expenses (Detail) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Restructuring Cost And Reserve [Line Items]
Employee Terminations	$ 9.0	$ 0.5	$ 29.9	$ 19.4
Other Restructuring Charges	6.7	1.1	24.8	13.7
Multi-Employer Pension Plan Charges	37.3	0.8	39.2	2.2
Impairment and Other	1.2	(4.7)	(0.1)	(4.6)
Total	54.2	(2.3)	93.8	30.7
Total Operating Segments | Business Services
Restructuring Cost And Reserve [Line Items]
Employee Terminations	4.6	(0.4)	16.7	17.5
Other Restructuring Charges	2.2	(0.7)	5.0	7.0
Multi-Employer Pension Plan Charges	0.1	0.7	1.8	1.9
Impairment and Other	0.1	(4.7)	(1.2)	(4.6)
Total	7.0	(5.1)	22.3	21.8
Total Operating Segments | Marketing Solutions
Restructuring Cost And Reserve [Line Items]
Employee Terminations	2.2	(0.1)	4.3	0.4
Other Restructuring Charges	1.3	0.1	1.8	0.1
Multi-Employer Pension Plan Charges	0.1	0.1	0.3	0.3
Impairment and Other	1.1		1.1
Total	4.7	0.1	7.5	0.8
Corporate
Restructuring Cost And Reserve [Line Items]
Employee Terminations	2.2	1.0	8.9	1.5
Other Restructuring Charges	3.2	1.7	18.0	6.6
Multi-Employer Pension Plan Charges	37.1		37.1
Impairment and Other	0.0		0.0
Total	$ 42.5	$ 2.7	$ 64.0	$ 8.1