ACCUMULATED OTHER COMPREHENSIVE INCOME (LOSS) (Tables)

9 Months Ended

Sep. 30, 2016

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 income (loss) in our Statements of Income for the periods indicated:

	Three Months Ended						Nine Months Ended
Details about Accumulated Other Comprehensive	September 30,						September 30,						Affected Line Item in the
Income (Loss) Components	2016			2015			2016			2015			Statements of Income
	(Thousands of dollars)
Pension and other postemployment benefit plan obligations (a)
Amortization of net loss	$	10,040		$	12,564		$	30,113		$	37,694
Amortization of unrecognized prior service cost	(909		)	(374		)	(2,725		)	(1,120		)
	9,131			12,190			27,388			36,574
Regulatory adjustments (b)	(8,943		)	(11,961		)	(26,824		)	(35,887		)
	188			229			564			687			Income before income taxes
	(72		)	(88		)	(217		)	(264		)	Income tax expense
Total reclassifications for the period	$	116		$	141		$	347		$	423		Net income

(a) These components of accumulated other comprehensive income (loss) are included in the computation of net periodic benefit cost. See Note 8 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 2 for additional disclosures of regulatory assets and liabilities.