Employee Benefit Plans Net Periodic Benefit Cost (Detail) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Pension Plan | UNITED STATES
Defined Benefit Plan and Other Postretirement Benefit Plans
Service Cost	$ 2.8	$ 2.3	$ 8.2	$ 6.9
Interest Cost	20.8	19.9	62.5	59.8
Expected Return on Plan Assets	(24.8)	(26.1)	(74.5)	(78.4)
Amortization of Net Actuarial Loss (Gain)	5.0	5.4	15.1	16.3
Amortization of Prior Service Credit	0.0	0.0	0.0	0.0
Net Periodic Benefit Cost (Credit)	3.8	1.5	11.3	4.6
Pension Plan | UNITED KINGDOM
Defined Benefit Plan and Other Postretirement Benefit Plans
Service Cost	0.0	0.0	0.0	0.0
Interest Cost	1.4	1.5	4.5	4.6
Expected Return on Plan Assets	(2.1)	(2.3)	(6.6)	(7.0)
Amortization of Net Actuarial Loss (Gain)	0.3	0.2	0.7	0.5
Amortization of Prior Service Credit	0.0	0.0	0.0	0.0
Net Periodic Benefit Cost (Credit)	(0.4)	(0.6)	(1.4)	(1.9)
OPEB Plan
Defined Benefit Plan and Other Postretirement Benefit Plans
Service Cost	0.0	0.0	0.0	0.0
Interest Cost	1.4	1.2	4.0	3.7
Expected Return on Plan Assets	(0.1)	(0.1)	(0.4)	(0.4)
Amortization of Net Actuarial Loss (Gain)	(0.7)	0.0	(1.9)	0.0
Amortization of Prior Service Credit	(0.1)	(0.1)	(0.2)	(0.2)
Net Periodic Benefit Cost (Credit)	$ 0.5	$ 1.0	$ 1.5	$ 3.1