Restructuring, Impairment and Other Charges - Narrative (Detail) $ in Millions	3 Months Ended
	Mar. 31, 2017 USD ($) Facility	Mar. 31, 2016 USD ($) Facility
Restructuring Cost And Reserve [Line Items]
Employee termination costs	$ 6.4	$ 4.9
Number of facilities closed | Facility		2
Impairment charges	0.5	$ (1.6)
Other restructuring charges	$ 1.6	1.5
Impairment gains, net		$ 1.6
Strategic Services
Restructuring Cost And Reserve [Line Items]
Number of facilities closed | Facility	1
Impairment charges	$ 0.5