ACCUMULATED OTHER COMPREHENSIVE INCOME (LOSS) (Tables)

9 Months Ended

Sep. 30, 2020

Accumulated Other Comprehensive Income (Loss) [Line Items]

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				Nine Months Ended				Affected Line Item in the
Details About Accumulated Other	September 30,				September 30,				Consolidated Statements
Comprehensive Loss Components	2020		2019		2020		2019		of Income
	(Thousands of dollars)
Pension and other postemployment benefit plan obligations (a)
Amortization of net loss	$	10,623	$	8,821	$	31,869	$	26,463
Amortization of unrecognized prior service credit	(29)		(168)		(87)		(504)
	10,594		8,653		31,782		25,959
Reclassification of stranded tax effects (b)	—		—		—		(1,218)
Regulatory adjustments (c)	(10,296)		(8,440)		(30,888)		(24,102)
	298		213		894		639		Income before income taxes
	(75)		(53)		(224)		(159)		Income tax expense
Total reclassifications for the period	$	223	$	160	$	670	$	480	Net income

(a) These components of accumulated other comprehensive loss are included in the computation of net periodic benefit cost. See Note 10 for additional detail of our net periodic benefit cost.

(b) Reflects the impact of the adoption of ASU 2018-02 in fiscal year 2019 related to stranded tax effects in accumulated other comprehensive income as a result of the Tax Cuts and Jobs Act of 2017. See Note 1 for additional information regarding our adoption of this standard.

(c) 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.