Restructuring, Impairment and Other - Narrative (Detail) - USD ($) $ in Millions	3 Months Ended			6 Months Ended
	Jun. 30, 2020	Mar. 31, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Restructuring Cost And Reserve [Line Items]
Employee termination costs	$ 13.0		$ 10.8	$ 21.1	$ 18.9
Other restructuring charges	13.9		4.5	18.1	12.7
Gain (loss) on sale of previously impaired assets	(0.2)			1.5
Multi-employer pension plan charges	$ 1.2		$ 0.7	1.9	$ 1.4
Goodwill impairment charge		$ 20.6		20.6
Business Services
Restructuring Cost And Reserve [Line Items]
Goodwill impairment charge		$ 20.6		$ 20.6