Regulatory Assets and Liabilities (Tables)

12 Months Ended

Dec. 31, 2019

Regulatory Assets and Liabilities Disclosure [Abstract]

Regulatory Assets

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	11	Various	$	85	$	1,328	$	87	$	1,500
Recoverable deferred taxes on AFUDC recorded in plant		Plant lives	—		271		—		264
Net AROs (a)	1, 12	Plant lives	—		269		—		452
Excess deferred taxes — TCJA	7	Various	39		239		—		296
Depreciation differences		One to twelve years	15		140		18		107
Environmental remediation costs	1, 12	Various	36		131		17		155
Benson biomass PPA termination and asset purchase		Ten years	9		73		10		86
Contract valuation adjustments (b)	1, 10	Term of related contract	20		62		17		77
Purchased power contract costs		Term of related contract	5		61		4		63
Laurentian biomass PPA termination		Five years	19		54		18		73
PI extended power uprate		Sixteen years	3		53		3		56
Losses on reacquired debt		Term of related debt	4		41		4		44
State commission adjustments		Plant lives	1		31		1		29
Property tax		Various	2		30		14		10
Conservation programs (c)	1	One to two years	27		26		42		28
Nuclear refueling outage costs	1	One to two years	43		17		37		14
Sales true-up and revenue decoupling		One to two years	54		16		38		7
Renewable resources and environmental initiatives		One to two years	72		10		39		9
Gas pipeline inspection and remediation costs		One to two years	26		8		28		3
Deferred purchased natural gas and electric energy costs		One to three years	6		6		57		13
Other		Various	22		69		30		40
Total regulatory assets			$	488	$	2,935	$	464	$	3,326

^(a) Includes amounts recorded for future recovery of AROs, less amounts recovered through nuclear decommissioning accruals and gains from decommissioning investments.

^(b) Includes the fair value of certain long-term PPAs used to meet energy capacity requirements and valuation adjustments on natural gas commodity purchases.

^(c) Includes costs for conservation programs, as well as incentives allowed in certain jurisdictions.

Regulatory Liabilities

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	$	75	$	3,523	$	157	$	3,715
Plant removal costs	1, 12	Plant lives	—		1,217		—		1,175
Effects of regulation on employee benefit costs (b)		Various	—		196		—		137
Renewable resources and environmental initiatives		Various	—		45		9		54
ITC deferrals (c)	1	Various	—		38		—		40
Deferred electric, natural gas and steam production costs		Less than one year	138		—		102		—
Contract valuation adjustments (d)	1, 10	Less than one year	19		—		26		—
Conservation programs (e)	1	Less than one year	37		—		36		—
DOE settlement		Less than one year	37		—		19		—
Other		Various	101		58		87		66
Total regulatory liabilities (f)			$	407	$	5,077	$	436	$	5,187

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

^(b)  Includes regulatory amortization and certain 2018 TCJA benefits approved by the CPUC to offset the PSCo prepaid pension asset.

^(c)  Includes impact of lower federal tax rate due to the TCJA.

^(d)  Includes the fair value of certain long-term PPAs used to meet energy capacity requirements and valuation adjustments on natural gas commodity purchases.

^(e)  Includes costs for conservation programs, as well as incentives allowed in certain jurisdictions.

^(f) 

Revenue subject to refund of $28 million and $29 million for 2019 and 2018, respectively, is included in other current liabilities.