Fair Value Measurements (Tables)

12 Months Ended

Dec. 31, 2020

Fair Value Disclosures [Abstract]

Fair value of assets and liabilities that are measured at fair value on a recurring basis

The following table presents the fair value at December 31, 2020 of our assets and liabilities that are measured at fair value on a recurring basis (dollars in thousands):

	Level 1		Level 2		Level 3		Other			Total
Assets
Risk management activities — derivative instruments:
Commodity contracts	$	—	$	9,016	$	4	$	(4,271)	(a)	$	4,749
Nuclear decommissioning trust:
Equity securities	29,796		—		—		(17,828)		(b)	11,968
U.S. commingled equity funds	—		—		—		610,055		(c)	610,055
U.S. Treasury debt	164,514		—		—		—			164,514
Corporate debt	—		149,509		—		—			149,509
Mortgage-backed securities	—		99,623		—		—			99,623
Municipal bonds	—		89,705		—		—			89,705
Other fixed income	—		13,061		—		—			13,061
Subtotal nuclear decommissioning trust	194,310		351,898		—		592,227			1,138,435
Other special use funds:
Equity securities	37,337		—		—		504		(b)	37,841
U.S. Treasury debt	203,220		—		—		—			203,220
Municipal bonds	—		13,448		—		—			13,448
Subtotal other special use funds	240,557		13,448		—		504			254,509
Total assets	$	434,867	$	374,362	$	4	$	588,460		$	1,397,693
Liabilities
Risk management activities — derivative instruments:
Commodity contracts	$	—	$	(20,498)	$	(1,107)	$	2,986	(a)	$	(18,619)

(a)Represents counterparty netting, margin, and collateral (see Note 16).

(b)Represents net pending securities sales and purchases.

(c)Valued using NAV as a practical expedient and, therefore, are not classified in the fair value hierarchy.

 The following table presents the fair value at December 31, 2019 of our assets and liabilities that are measured at fair value on a recurring basis (dollars in thousands):

	Level 1		Level 2		Level 3		Other			Total
Assets
Risk management activities — derivative instruments:
Commodity contracts	$	—	$	551	$	33	$	(69)	(a)	$	515
Nuclear decommissioning trust:
Equity securities	10,872		—		—		2,401		(b)	13,273
U.S. commingled equity funds	—		—		—		518,844		(c)	518,844
U.S. Treasury debt	160,607		—		—		—			160,607
Corporate debt	—		115,869		—		—			115,869
Mortgage-backed securities	—		118,795		—		—			118,795
Municipal bonds	—		73,040		—		—			73,040
Other fixed income	—		10,347		—		—			10,347
Subtotal nuclear decommissioning trust	171,479		318,051		—		521,245			1,010,775
Other special use funds:
Equity securities	7,142		—		—		474		(b)	7,616
U.S. Treasury debt	232,848		—		—		—			232,848
Municipal bonds	—		4,631		—		—			4,631
Subtotal other special use funds	239,990		4,631		—		474			245,095
Total assets	$	411,469	$	323,233	$	33	$	521,650		$	1,256,385
Liabilities
Risk management activities — derivative instruments:
Commodity contracts	$	—	$	(67,992)	$	(3,429)	$	(711)	(a)	$	(72,132)

(a)Represents counterparty netting, margin, and collateral (see Note 16).

(b)Represents net pending securities sales and purchases.

(c)Valued using NAV as a practical expedient and, therefore, are not classified in the fair value hierarchy.