Restructuring, Integration and Acquisition-Related Costs - Additional Information (Detail) $ in Millions	3 Months Ended				6 Months Ended
	Jun. 30, 2018 USD ($) Employee	Mar. 31, 2018 USD ($) Employee	Jun. 30, 2017 USD ($) Employee	Mar. 31, 2017 USD ($) Employee	Jun. 30, 2018 USD ($)	Jun. 30, 2017 USD ($)	Dec. 31, 2017 USD ($)
Restructuring Cost and Reserve [Line Items]
Restructuring, integration and acquisition-related costs	$ 14.0	$ 8.0	$ 9.9	$ 10.8	$ 22.0	$ 20.7
Restructuring, integration and acquisition-related costs			$ 9.9
Restructuring related liability, current	19.7				19.7		$ 30.0
Workforce Reduction
Restructuring Cost and Reserve [Line Items]
Restructuring, integration and acquisition-related costs	$ 3.3	$ 4.1		$ 2.7
Approximate number of employees terminated \| Employee	50	100	125	35
Restructuring, integration and acquisition-related costs			$ 7.8
Workforce Reduction \| Accounts Payable and Accrued Liabilities
Restructuring Cost and Reserve [Line Items]
Restructuring related liability, current	$ 9.8				9.8
Facility-Related, Including Lease Termination Obligation
Restructuring Cost and Reserve [Line Items]
Restructuring, integration and acquisition-related costs	1.5	$ 1.4		$ 0.1
Restructuring, integration and acquisition-related costs			0.2
Facility-Related, Including Lease Termination Obligation \| Accounts Payable and Accrued Liabilities
Restructuring Cost and Reserve [Line Items]
Restructuring related liability, current	2.6				2.6
Facility-Related, Including Lease Termination Obligation \| Other Noncurrent Liabilities
Restructuring Cost and Reserve [Line Items]
Restructuring related liability, non-current	1.4				$ 1.4
Integration and Acquisition Related
Restructuring Cost and Reserve [Line Items]
Restructuring, integration and acquisition-related costs	$ 9.2	$ 2.5		$ 8.0
Integration Related
Restructuring Cost and Reserve [Line Items]
Restructuring, integration and acquisition-related costs			1.9
Acquisition Related
Restructuring Cost and Reserve [Line Items]
Restructuring, integration and acquisition-related costs			$ 1.9

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