Other Comprehensive Income (Tables)

9 Months Ended

Sep. 30, 2017

Stockholders' Equity Note [Abstract]

Changes in Accumulated Other Comprehensive Loss, Net of Tax

Changes in accumulated other comprehensive loss, net of tax, for the three and nine months ended Sept. 30, 2017 and 2016 were as follows:

	Three Months Ended Sept. 30, 2017
(Thousands of Dollars)	Gains and Losses on Cash Flow Hedges			Defined Benefit and Postretirement Items			Total
Accumulated other comprehensive loss at July 1	$	(22,284	)	$	(218	)	$	(22,502	)
Losses reclassified from net accumulated other comprehensive loss	257			1			258
Net current period other comprehensive income	257			1			258
Accumulated other comprehensive loss at Sept. 30	$	(22,027	)	$	(217	)	$	(22,244	)

	Three Months Ended Sept. 30, 2016
(Thousands of Dollars)	Gains and Losses on Cash Flow Hedges			Defined Benefit and Postretirement Items			Total
Accumulated other comprehensive loss at July 1	$	(23,308	)	$	(217	)	$	(23,525	)
Other comprehensive loss before reclassifications	(1		)	—			(1		)
Losses reclassified from net accumulated other comprehensive loss	266			—			266
Net current period other comprehensive income	265			—			265
Accumulated other comprehensive loss at Sept. 30	$	(23,043	)	$	(217	)	$	(23,260	)

	Nine Months Ended Sept. 30, 2017
(Thousands of Dollars)	Gains and Losses on Cash Flow Hedges			Defined Benefit and Postretirement Items			Total
Accumulated other comprehensive loss at Jan. 1	$	(22,780	)	$	(220	)	$	(23,000	)
Losses reclassified from net accumulated other comprehensive loss	753			3			756
Net current period other comprehensive income	753			3			756
Accumulated other comprehensive loss at Sept. 30	$	(22,027	)	$	(217	)	$	(22,244	)

	Nine Months Ended Sept. 30, 2016
(Thousands of Dollars)	Gains and Losses on Cash Flow Hedges			Defined Benefit and Postretirement Items			Total
Accumulated other comprehensive loss at Jan. 1	$	(23,836	)	$	—		$	(23,836	)
Other comprehensive income (loss) before reclassifications	1			(219		)	(218		)
Losses reclassified from net accumulated other comprehensive loss	792			2			794
Net current period other comprehensive loss	793			(217		)	576
Accumulated other comprehensive loss at Sept. 30	$	(23,043	)	$	(217	)	$	(23,260	)

Reclassifications out of Accumulated Other Comprehensive Loss

Reclassifications from accumulated other comprehensive loss for the three and nine months ended Sept. 30, 2017 and 2016 were as follows:

	Amounts Reclassified from Accumulated Other Comprehensive Loss
(Thousands of Dollars)	Three Months Ended Sept. 30, 2017				Three Months Ended Sept. 30, 2016
Losses on cash flow hedges:
Interest rate derivatives	$	407		(a)	$	407		(a)
Vehicle fuel derivatives	—			(b)	21			(b)
Total, pre-tax	$	407			$	428
Tax benefit	(150		)		(162		)
Total, net of tax	$	257			$	266
Defined benefit pension and postretirement losses:
Amortization of net loss	$	2		(c)	$	—		(c)
Total, pre-tax	2				—
Tax benefit	(1		)		—
Total, net of tax	1				—
Total amounts reclassified, net of tax	$	258			$	266

	Amounts Reclassified from Accumulated Other Comprehensive Loss
(Thousands of Dollars)	Nine Months Ended Sept. 30, 2017				Nine Months Ended Sept. 30, 2016
Losses on cash flow hedges:
Interest rate derivatives	$	1,208		(a)	$	1,211		(a)
Vehicle fuel derivatives	—			(b)	67			(b)
Total, pre-tax	1,208				1,278
Tax benefit	(455		)		(486		)
Total, net of tax	$	753			$	792
Defined benefit pension and postretirement losses:
Amortization of net loss	$	6		(c)	$	—		(c)
Total, pre-tax	6				—
Tax benefit	(3		)		—
Total, net of tax	3				—
Total amounts reclassified, net of tax	$	756			$	792

^(a)  Included in interest charges.

^(b)  Included in O&M expenses.