Restructuring - Summary of Restructuring Activities (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Restructuring Reserve [Roll Forward]
Accrual as of beginning of period	$ 98.0	$ 74.0	$ 71.8
Charges	88.0	70.9	63.6
Utilization, Cash	(72.6)	(45.6)	(56.7)
Utilization, Non-cash	(4.7)	(1.3)	(4.7)
Accrual as of end of period	108.7	98.0	74.0
Employee termination benefits
Restructuring Reserve [Roll Forward]
Accrual as of beginning of period	93.0	69.4	66.5
Charges	74.5	62.9	54.1
Utilization, Cash	(64.2)	(39.3)	(51.2)
Utilization, Non-cash	0.0	0.0	0.0
Accrual as of end of period	103.3	93.0	69.4
Asset impairments
Restructuring Reserve [Roll Forward]
Accrual as of beginning of period	0.0	0.0	0.0
Charges	4.7	1.3	4.7
Utilization, Cash	0.0	0.0	0.0
Utilization, Non-cash	(4.7)	(1.3)	(4.7)
Accrual as of end of period	0.0	0.0	0.0
Contract termination costs
Restructuring Reserve [Roll Forward]
Accrual as of beginning of period	5.0	4.6	5.3
Charges	1.5	1.7	0.1
Utilization, Cash	(1.1)	(1.3)	(0.8)
Utilization, Non-cash	0.0	0.0	0.0
Accrual as of end of period	5.4	5.0	4.6
Other related costs
Restructuring Reserve [Roll Forward]
Accrual as of beginning of period	0.0	0.0	0.0
Charges	7.3	5.0	4.7
Utilization, Cash	(7.3)	(5.0)	(4.7)
Utilization, Non-cash	0.0	0.0	0.0
Accrual as of end of period	$ 0.0	$ 0.0	$ 0.0