Other Comprehensive Income (Tables)

9 Months Ended

Sep. 30, 2019

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, 2019 and 2018:

	Three Months Ended Sept. 30, 2019									Three Months Ended Sept. 30, 2018
(Millions of Dollars)	Gains and Losses on Cash Flow Hedges			Defined Benefit Pension and Postretirement Items			Total			Gains and Losses on Cash Flow Hedges			Defined Benefit Pension and Postretirement Items			Total
Accumulated other comprehensive loss at July 1	$	(24.7	)	$	(0.2	)	$	(24.9	)	$	(25.8	)	$	(0.3	)	$	(26.1	)
Other comprehensive loss before reclassifications (net of taxes of $0, $0, $0 and $(0.1), respectively)	—			—			—			—			(0.2		)	(0.2		)
Losses reclassified from net accumulated other comprehensive loss:
Interest rate derivatives (net of taxes of $0.1, $0, $0.1 and $0, respectively) (a)	0.3			—			0.3			0.3			—			0.3
Amortization of net actuarial loss (net of taxes of $0, $0, $0 and $0.1, respectively)	—			—			—			—			0.2			0.2
Net current period other comprehensive income	0.3			—			0.3			0.3			—			0.3
Accumulated other comprehensive loss at Sept. 30	$	(24.4	)	$	(0.2	)	$	(24.6	)	$	(25.5	)	$	(0.3	)	$	(25.8	)

	Nine Months Ended Sept. 30, 2019									Nine Months Ended Sept. 30, 2018
(Millions of Dollars)	Gains and Losses on Cash Flow Hedges			Defined Benefit Pension and Postretirement Items			Total			Gains and Losses on Cash Flow Hedges			Defined Benefit Pension and Postretirement Items			Total
Accumulated other comprehensive loss at Jan. 1	$	(25.3	)	$	(0.2	)	$	(25.5	)	$	(26.4	)	$	(0.3	)	$	(26.7	)
Other comprehensive loss before reclassifications (net of taxes of $0, $0, $0 and $(0.1), respectively	—			—			—			—			(0.2		)	(0.2		)
Losses reclassified from net accumulated other comprehensive loss:
Interest rate derivatives (net of taxes of $0.3, $0, $0.3 and $0, respectively) (a)	0.9			—			0.9			0.9			—			0.9
Amortization of net actuarial loss (net of taxes of $0, $0, $0 and $0.1, respectively)	—			—			—			—			0.2			0.2
Net current period other comprehensive income	0.9			—			0.9			0.9			—			0.9
Accumulated other comprehensive loss at Sept. 30	$	(24.4	)	$	(0.2	)	$	(24.6	)	$	(25.5	)	$	(0.3	)	$	(25.8	)

^(a) 

Included in interest charges.