EMPLOYEE BENEFIT PLANS (Tables)

3 Months Ended

Mar. 31, 2025

Employee Benefit Plans [Line Items]

Schedule of Net Benefit Costs [Table Text Block]

The following tables set forth the components of net periodic benefit cost for our pension, inclusive of our defined benefit pension plan and supplemental executive retirement plan, and other postemployment benefit plans for the periods indicated:

	Pension Benefits
	Three Months Ended
	March 31,
	2025		2024
	(Thousands of dollars)
Components of net periodic benefit cost (credit)
Service cost	$	1,337	$	1,551
Interest cost (a)	10,042		10,281
Expected return on assets (a)	(11,910)		(14,757)
Amortization of unrecognized prior service cost (a)	93		93
Amortization of net loss (a)	1,865		1,446
Net periodic benefit cost (credit)	$	1,427	$	(1,386)
(a) These amounts, net of any amounts capitalized as a regulatory asset, have been recognized as other (income) expense, net in the consolidated statement of income. See Note 11 for additional detail.

	Other Postemployment Benefits
	Three Months Ended
	March 31,
	2025		2024
	(Thousands of dollars)
Components of net periodic benefit cost (credit)
Service cost	$	123	$	152
Interest cost (a)	2,069		2,045
Expected return on assets (a)	(2,212)		(2,284)
Amortization of unrecognized prior service cost (credit) (a)	—		—
Amortization of net (gain) (a)	(31)		(4)
Net periodic benefit cost (credit)	$	(51)	$	(91)
(a) These amounts, net of any amounts capitalized as a regulatory asset, have been recognized as other (income) expense, net in the consolidated statement of income. See Note 11 for additional detail.