Regulatory Assets and Liabilities (Tables)

12 Months Ended

Dec. 31, 2019

Components of regulatory assets:



(Millions of Dollars)	See Note(s)	Remaining Amortization Period	Dec. 31, 2019				Dec. 31, 2018
Regulatory Assets			Current		Noncurrent		Current		Noncurrent
Pension and retiree medical obligations	9	Various	$	11.1	$	203.5	$	12.6	$	222.1
Excess deferred taxes — TCJA	7	Various	1.7		52.0		—		55.9
Recoverable deferred taxes on AFUDC recorded in plant		Plant lives	—		34.1		—		27.9
Net AROs ^(a)	1, 10	Plant lives	—		26.9		—		25.7
Losses on reacquired debt		Term of related debt	0.8		21.0		0.8		21.9
Conservation programs ^(b)	1	One to two years	0.6		1.1		0.7		0.6
Other		Various	5.8		25.4		11.9		12.1
Total regulatory assets			$	20.0	$	364.0	$	26.0	$	366.2


^(a)	Includes amounts recorded for future recovery of AROs.

^(b)

Includes costs for conservation programs, as well as incentives allowed in certain jurisdictions.

Components of regulatory liabilities:



(Millions of Dollars)	See Note(s)	Remaining Amortization Period	Dec. 31, 2019				Dec. 31, 2018
Regulatory Liabilities			Current		Noncurrent		Current		Noncurrent
Deferred income tax adjustments and TCJA refunds ^(a)	7	Various	$	6.9	$	534.9	$	2.2	$	569.8
Plant removal costs	1, 10	Plant lives	—		174.5		—		187.7
Revenue subject to refund		One to two years	14.6		1.1		11.3		8.1
Gain from asset sales		Various	—		2.4		—		2.4
Deferred electric energy costs		Less than one year	81.6		—		56.5		—
Contract valuation adjustments ^(b)	1, 8	Less than one year	11.7		—		14.7		—
Other		Various	3.3		19.4		1.1		12.9
Total regulatory liabilities^(c)			$	118.1	$	732.3	$	85.8	$	780.9


^(a)	Includes the revaluation of recoverable/regulated plant ADIT and revaluation impact of non-plant ADIT due to the TCJA.


^(b)	Includes the fair value of certain long-term PPAs used to meet energy capacity requirements.

^(c)

Revenue subject to refund of $3.9 million for 2019 and none for 2018 is included in other current liabilities.