ACCUMULATED OTHER COMPREHENSIVE INCOME (LOSS) (Tables)

3 Months Ended

Mar. 31, 2024

Accumulated Other Comprehensive Income (Loss), Net of Tax [Abstract]

Reclassification out of Accumulated Other Comprehensive Income [Table Text Block]

The following table sets forth the effect of reclassifications from accumulated other comprehensive loss in our consolidated statements of income for the periods indicated:

	Three Months Ended				Affected Line Item in the
Details About Accumulated Other	March 31,				Consolidated Statements
Comprehensive Loss Components	2024		2023		of Income
	(Thousands of dollars)
Pension and other postemployment benefit plan obligations (a)
Amortization of net (gain) loss	$	1,442	$	490
Amortization of unrecognized prior service cost (credit)	93		131
	1,535		621
Regulatory adjustments (b)	(1,535)		(621)
Total pension and other postemployment benefit obligations	—		—
Available-for-sale securities
Unrealized holding gains (losses) on available-for-sale securities	(12)		—
Amounts reclassified from accumulated other comprehensive income	(1)		—
Total available-for-sale securities	(13)		—
	(13)		—		Income before income taxes
	3		—		Income tax expense
Total reclassifications for the period	$	(10)	$	—	Net income

(a) These components of accumulated other comprehensive loss are included in the computation of net periodic benefit cost. See Note 9 for additional detail of our net periodic benefit cost.

(b) Regulatory adjustments represent pension and other postemployment benefit costs expected to be recovered through rates and are deferred as part of our regulatory assets. See Note 3 for additional disclosures of regulatory assets and liabilities.