Pension and Postretirement Benefits - Components of Net Periodic Benefit Expense (Detail) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Pension Plans
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 1.6	$ 2.1	$ 3.2	$ 3.9
Interest cost	70.9	81.4	140.8	161.9
Expected return on plan assets	(90.1)	(100.0)	(179.5)	(199.4)
Amortization of prior service benefit	(1.2)	(1.4)	(2.5)	(2.8)
Recognized net actuarial loss	45.3	39.4	89.0	78.2
Curtailment gain	(5.2)	0.0	(5.2)	0.0
Net periodic pension/postretirement benefit expense	21.3	21.5	45.8	41.8
U.S. Plans
Defined Benefit Plan Disclosure [Line Items]
Service cost	0.0	0.0	0.0	0.0
Interest cost	53.2	58.1	105.7	115.7
Expected return on plan assets	(58.8)	(63.2)	(117.6)	(126.6)
Amortization of prior service benefit	(0.7)	(0.7)	(1.3)	(1.3)
Recognized net actuarial loss	32.3	29.3	63.2	58.0
Curtailment gain	0.0	0.0	0.0	0.0
Net periodic pension/postretirement benefit expense	26.0	23.5	50.0	45.8
International Plans
Defined Benefit Plan Disclosure [Line Items]
Service cost	1.6	2.1	3.2	3.9
Interest cost	17.7	23.3	35.1	46.2
Expected return on plan assets	(31.3)	(36.8)	(61.9)	(72.8)
Amortization of prior service benefit	(0.5)	(0.7)	(1.2)	(1.5)
Recognized net actuarial loss	13.0	10.1	25.8	20.2
Curtailment gain	(5.2)	0.0	(5.2)	0.0
Net periodic pension/postretirement benefit expense	(4.7)	(2.0)	(4.2)	(4.0)
Other Postretirement Benefit Plans
Defined Benefit Plan Disclosure [Line Items]
Service cost	0.1	0.1	0.2	0.2
Interest cost	1.5	1.6	3.0	3.2
Expected return on plan assets	(0.1)	(0.1)	(0.2)	(0.2)
Amortization of prior service benefit	(0.1)	0.0	(0.2)	0.0
Recognized net actuarial loss	0.3	0.3	0.6	0.6
Net periodic pension/postretirement benefit expense	$ 1.7	$ 1.9	$ 3.4	$ 3.8