Other Postretirement Employee Benefit Plans (Funded Status Of The Domestic Plans) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Change in plan assets:
Fair value of plan assets	$ 3,204.2	$ 2,911.1
Other postretirement benefits
Change in benefit obligation:
Benefit obligation at beginning of year	174.6	193.4
Service cost	0.7	0.7
Interest cost	5.6	6.6
Amendments, curtailments and other	0.4	(6.5)
Actuarial loss (gain)	1.5	(5.0)
Retiree contributions	2.9	3.2
Benefits paid	(18.4)	(17.8)
Benefit obligation at end of year	167.3	174.6
Change in plan assets:
Fair value of plan assets	0.0	0.0
Funded status	$ (167.3)	$ (174.6)