Pensions and Postretirement Benefits Other Than Pensions (Schedule of Company's Postretirement Plans Benefit Obligations) (Details) - Postretirement [Member] - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2023	Dec. 31, 2022
Benefit obligation at beginning of year		$ 266.4	$ 342.2
Service cost		1.4	1.8
Interest cost		13.3	6.9
Plan participants' contributions		0.0	5.7
Actuarial (gains) losses		(7.4)	(53.7)
Benefits paid, net of Medicare Part D subsidy	[1]	(32.4)	(39.8)
Amendments		0.0	3.3
Benefit obligation at end of year		$ 241.3	$ 266.4

[1] Actuarial gains in fiscal year 2023 primarily due to plan experience. Actuarial gains in fiscal year 2022 primarily resulted from changes in discount rates. (2) Amounts are net of Medicare Part D subsidy of $0.4 million in both 2023 and 2022.