Pension Benefits, Other Postretirement Benefits and Employee Savings and Investment Plans (Summary of Changes in Fair Value of Guaranteed Deposit Account's Level 3 Assets) (Details) - Pension Benefits $ in Millions	12 Months Ended
	Dec. 31, 2023 USD ($)
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair value of plan assets as of January 1	$ 26.3
Fair value of plan assets as of December 31	26.7
Level 3
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair value of plan assets as of January 1	1.1
Fair value of plan assets as of December 31	1.1
Guaranteed deposit account
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair value of plan assets as of January 1	1.1
Fair value of plan assets as of December 31	1.1
Guaranteed deposit account | Level 3
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair value of plan assets as of January 1	1.1
Change in unrealized gain (loss)	0.0
Purchases, sales, issuances and settlements (net)	0.0
Fair value of plan assets as of December 31	$ 1.1