Restructuring, Impairment and Other - Schedule of Net Restructuring, Impairment and Other Expenses (Detail) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Restructuring Cost And Reserve [Line Items]
Employee Terminations	$ 13.0	$ 10.8	$ 21.1	$ 18.9
Other Restructuring Charges	13.9	4.5	18.1	12.7
Multi-Employer Pension Plan Charges	1.2	0.7	1.9	1.4
Impairment and Other	0.4		19.3	0.1
Total	28.5	16.0	60.4	33.1
Total Operating Segments | Business Services
Restructuring Cost And Reserve [Line Items]
Employee Terminations	6.6	10.2	12.4	18.0
Other Restructuring Charges	1.7	3.0	2.8	7.7
Multi-Employer Pension Plan Charges	1.1	0.6	1.7	1.2
Impairment and Other	0.4		19.3	0.1
Total	9.8	13.8	36.2	27.0
Total Operating Segments | Marketing Solutions
Restructuring Cost And Reserve [Line Items]
Employee Terminations	1.6	0.3	2.0	0.4
Other Restructuring Charges	0.5	0.1	0.5	0.1
Multi-Employer Pension Plan Charges	0.1	0.1	0.2	0.2
Impairment and Other	0.0		0.0
Total	2.2	0.5	2.7	0.7
Corporate
Restructuring Cost And Reserve [Line Items]
Employee Terminations	4.8	0.3	6.7	0.5
Other Restructuring Charges	11.7	1.4	14.8	4.9
Multi-Employer Pension Plan Charges	0.0		0.0
Impairment and Other	0.0		0.0
Total	$ 16.5	$ 1.7	$ 21.5	$ 5.4