Pension And Other Postretirement Benefit Plans (Components Of Net Periodic Cost) (Detail) - Pension Plans, Defined Benefit - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 1.2	$ 1.2	$ 3.6	$ 3.5
Interest cost	7.2	8.2	21.6	24.5
Expected return on plan assets	(13.9)	(14.5)	(41.7)	(43.3)
Defined Benefit Plan, Amortization of Prior Service Cost (Credit)	(0.1)	(0.2)	(0.3)	(0.5)
Amortization of net loss (gain)	3.5	2.9	10.5	8.7
Net periodic cost	$ (2.1)	$ (2.4)	$ (6.3)	$ (7.1)