Pension and Other Postretirement Benefit Plans (Tables)

3 Months Ended

Mar. 31, 2024

Retirement Benefits [Abstract]

Components of Net Periodic Benefit Cost (Credit)

Components of Net Periodic Benefit Cost (Credit)	Pension		Other Postretirement
Three Months Ended March 31,	2024	2023	2024	2023
Millions
Service Cost	$1.6	$1.6	$0.4	$0.6
Non-Service Cost Components (a)
Interest Cost	9.7	10.1	1.0	1.5
Expected Return on Plan Assets	(11.2)	(10.9)	(2.8)	(2.8)
Amortization of Prior Service Credits	—	—	(2.9)	(1.8)
Amortization of Net Loss	1.6	1.4	(0.8)	(0.5)
Net Periodic Benefit Cost (Credit)	$1.7	$2.2	$(5.1)	$(3.0)

(a)These components of net periodic benefit cost (credit) are included in the line item “Other” under Other Income (Expense) on the Consolidated Statement of Income.