Fair Value of Financial Instruments (Tables)

12 Months Ended

Dec. 31, 2020

Fair Value of Financial Instruments [Abstract]

Schedule of Fair Value, Assets and Liabilities Measured on Recurring Basis [Table Text Block]

The Company’s financial assets and liabilities whose values were recognized at fair value are as follows by level within the fair value hierarchy (in millions): 

	As of December 31, 2020
	Level 1		Level 2		Level 3		Other(2)		Total
Assets:
Cash equivalents	$	255	$	—	$	—	$	—	$	255
Nuclear decommissioning trust: (1)
Debt securities:
Domestic government	9		11		—		—		20
Corporate credit	—		13		—		—		13
Money market funds measured at NAV (2)	—		—		—		12		12
Non-qualified benefit plan trust: (3)
Money market funds	1		—		—		—		1
Equity securities—domestic	7		—		—		—		7
Debt securities—domestic government	1		—		—		—		1
Price risk management activities: (1) (4)
Electricity	—		4		4		—		8
Natural gas	—		36		1		—		37
	$	273	$	64	$	5	$	12	$	354
Liabilities:
Price risk management activities: (1) (4)
Electricity	$	—	$	5	$	141	$	—	$	146
Natural gas	—		4		1		—		5
	$	—	$	9	$	142	$	—	$	151

(1)Activities are subject to regulation, with certain gains and losses deferred pursuant to regulatory accounting and included in regulatory assets or regulatory liabilities as appropriate.

(2)Assets are measured at NAV as a practical expedient and not subject to hierarchy level classification disclosure.

(3)Excludes insurance policies of $33 million, which are recorded at cash surrender value.

(4)For further information regarding price risk management derivatives, see Note 6, Risk Management.

	As of December 31, 2019
	Level 1		Level 2		Level 3		Other(2)		Total
Assets:
Cash equivalents	$	26	$	—	$	—	$	—	$	26
Nuclear decommissioning trust: (1)
Debt securities:
Domestic government	8		16		—		—		24
Corporate credit	—		9		—		—		9
Money market funds measured at NAV (2)	—		—		—		13		13
Non-qualified benefit plan trust: (3)
Money market funds	1		—		—		—		1
Equity securities—domestic	7		—		—		—		7
Debt securities—domestic government	1		—		—		—		1
Price risk management activities: (1) (4)
Electricity	—		9		7		—		16
Natural gas	—		21		1		—		22
	$	43	$	55	$	8	$	13	$	119
Liabilities:
Price risk management activities: (1) (4)
Electricity	$	—	$	14	$	105	$	—	$	119
Natural gas	—		12		—		—		12
	$	—	$	26	$	105	$	—	$	131

(1)Activities are subject to regulation, with certain gains and losses deferred pursuant to regulatory accounting and included in regulatory assets or regulatory liabilities as appropriate.

(2)Assets are measured at NAV as a practical expedient and not subject to hierarchy level classification disclosure.

(3)Excludes insurance policies of $29 million, which are recorded at cash surrender value.

(4)For further information regarding price risk management derivatives, see Note 6, Risk Management.

The fair values of the Company’s pension plan assets and other postretirement benefit plan assets by asset category are as follows (in millions):

	Level 1		Level 2		Level 3		Other *		Total
As of December 31, 2020:
Defined Benefit Pension Plan assets:
Equity securities—Domestic	$	49	$	—	$	—	$	—	$	49
Investments measured at NAV:
Money market funds	—		—		—		6		6
Collective trust funds	—		—		—		692		692
Private equity funds	—		—		—		6		6
	$	49	$	—	$	—	$	704	$	753
Other Postretirement Benefit Plans assets:
Money market funds	$	4	$	—	$	—	$	—	$	4
Equity securities:
Domestic	—		3		—		—		3
International	9		—		—		—		9
Debt securities—Domestic	—		5		—		—		5
Investments measured at NAV:
Money market funds	—		—		—		5		5
Collective trust funds	—		—		—		9		9
	$	13	$	8	$	—	$	14	$	35
As of December 31, 2019:
Defined Benefit Pension Plan assets:
Equity securities—Domestic	$	49	$	—	$	—	$	—	$	49
Investments measured at NAV:
Money market funds	—		—		—		5		5
Collective trust funds	—		—		—		632		632
Private equity funds	—		—		—		9		9
	$	49	$	—	$	—	$	646	$	695
Other Postretirement Benefit Plans assets:
Money market funds	$	4	$	—	$	—	$	—	$	4
Equity securities:
Domestic	—		3		—		—		3
International	9		—		—		—		9
Debt securities—Domestic government	—		5		—		—		5
Investments measured at NAV:
Money market funds	—		—		—		5		5
Collective trust funds	—		—		—		8		8
	$	13	$	8	$	—	$	13	$	34

*Assets are measured at NAV as a practical expedient and not subject to hierarchy level classification disclosure. These assets are listed in the totals of the fair value hierarchy to permit the reconciliation to amounts presented in the financial statements.

Fair Value Option, Disclosures [Table Text Block]

Quantitative information regarding the significant, unobservable inputs used in the measurement of Level 3 assets and liabilities from price risk management activities is presented below:

						Significant	Price per Unit
	Fair Value				Valuation	Unobservable					Weighted
Commodity Contracts	Assets		Liabilities		Technique	Input	Low		High		Average
	(in millions)
As of December 31, 2020:
Electricity physical forwards	$	—	$	141	Discounted cash flow	Electricity forward price (per MWh)	$	11.17	$	51.18	$	29.74
Natural gas financial swaps	1		1		Discounted cash flow	Natural gas forward price (per Dth)	1.52		4.33		2.29
Electricity financial futures	4		—		Discounted cash flow	Electricity forward price (per MWh)	8.78		58.42		43.71
	$	5	$	142
As of December 31, 2019:
Electricity physical forwards	$	—	$	104	Discounted cash flow	Electricity forward price (per MWh)	$	12.53	$	59.00	$	36.92
Natural gas financial swaps	1		—		Discounted cash flow	Natural gas forward price (per Dth)	1.39		3.73		1.90
Electricity financial futures	7		1		Discounted cash flow	Electricity forward price (per MWh)	10.57		66.32		45.11
	$	8	$	105

Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Table Text Block]

Changes in the fair value of net liabilities from price risk management activities (net of assets from price risk management activities) classified as Level 3 in the fair value hierarchy were as follows (in millions):

	Years Ended December 31,
	2020		2019
Net liabilities from price risk management activities as of beginning of year	$	97	$	88
Net realized and unrealized losses/(gains) *	38		10
Net transfers from Level 3 to Level 2	2		(1)
Net liabilities from price risk management activities as of end of year	$	137	$	97
Level 3 net unrealized losses/(gains) that have been fully offset by the effect of regulatory accounting	$	47	$	16

* Includes $9 million in net realized gains in 2020 and $6 million in 2019.