v3.26.1
EMPLOYEE BENEFIT PLANS (Tables)
 3 Months Ended
Mar. 31, 2026
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 (credit) for our pension, inclusive of our defined benefit pension plan, supplemental executive retirement plan, and other postemployment benefit plans for the periods indicated:

Pension Benefits
Three Months Ended
March 31,
20262025
(Thousands of dollars)
Components of net periodic benefit cost (credit)
 
Service cost$1,291 $1,337 
Interest cost (a)
9,525 10,042 
Expected return on assets (a)
(10,490)(11,910)
Amortization of unrecognized prior service cost (credit) (a)
93 93 
Amortization of net loss (gain) (a)
4,220 1,865 
Net periodic benefit cost (credit)
$4,639 $1,427 
(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,
20262025
(Thousands of dollars)
Components of net periodic benefit cost (credit)
Service cost$110 $123 
Interest cost (a)
2,020 2,069 
Expected return on assets (a)
(2,194)(2,212)
Amortization of unrecognized prior service cost (credit) (a)
— — 
Amortization of net loss (gain) (a)
(8)(31)
Net periodic benefit cost (credit)
$(72)$(51)
(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.