Benefit Plans and Other Postretirement Benefits (Tables)

6 Months Ended

Jun. 30, 2020

Retirement Benefits [Abstract]

Components of Net Periodic Benefit Cost

Components of Net Periodic Benefit Cost

	Three Months Ended June 30
	2020		2019		2020		2019
(Millions of Dollars)	Pension Benefits				Postretirement Health Care Benefits
Service cost	$	1.2	$	1.1	$	—	$	—
Interest cost (a)	1.2		1.4		0.1		0.1
Expected return on plan assets (a)	(2.1)		(2.0)		—		—
Amortization of prior service credit (a)	—		—		(0.1)		(0.1)
Amortization of net loss (a)	1.2		1.1		0.1		0.1
Net periodic benefit cost	$	1.5	$	1.6	$	0.1	$	0.1
Costs not recognized due to effects of regulation	1.8		—		—		—
Net benefit cost recognized for financial reporting	$	3.3	$	1.6	$	0.1	$	0.1

	Six Months Ended June 30
	2020		2019		2020		2019
(Millions of Dollars)	Pension Benefits				Postretirement Health Care Benefits
Service cost	$	2.3	$	2.2	$	—	$	—
Interest cost (a)	2.4		2.9		0.2		0.3
Expected return on plan assets (a)	(4.2)		(4.2)		—		—
Amortization of prior service credit (a)	—		—		(0.1)		(0.2)
Amortization of net loss (a)	2.4		2.2		0.1		0.1
Net periodic benefit cost	$	2.9	$	3.1	$	0.2	$	0.2
Costs not recognized due to effects of regulation	3.7		0.2		—		—
Net benefit cost recognized for financial reporting	$	6.6	$	3.3	$	0.2	$	0.2

^(a)  The components of net periodic cost other than the service cost component are included in the line item “other expense, net” in the consolidated statement of income or capitalized on the consolidated balance sheet as a regulatory asset.

^[1]

[1] The components of net periodic cost other than the service cost component are included in the line item “other expense, net” in the consolidated statement of income or capitalized on the consolidated balance sheet as a regulatory asset.