Fair Value Measurements (Tables)

12 Months Ended

Dec. 31, 2019

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, 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 17.

(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, 2018 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
Cash equivalents	$	1,200	$	—		$	—		$	—			$	1,200
Risk management activities — derivative instruments:
Commodity contracts	—		3,140			2			(2,029		)	(a)	1,113
Nuclear decommissioning trust:
Equity securities	5,203		—			—			2,148			(b)	7,351
U.S. commingled equity funds	—		—			—			396,805			(c)	396,805
U.S. Treasury debt	148,173		—			—			—				148,173
Corporate debt	—		96,656			—			—				96,656
Mortgage-backed securities	—		113,115			—			—				113,115
Municipal bonds	—		79,073			—			—				79,073
Other fixed income	—		9,961			—			—				9,961
Subtotal nuclear decommissioning trust	153,376		298,805			—			398,953				851,134
Other special use funds:
Equity securities	45,130		—			—			593			(b)	45,723
U.S. Treasury debt	173,310		—			—			—				173,310
Municipal bonds	—		17,068			—			—				17,068
Subtotal other special use funds	218,440		17,068			—			593				236,101
Total assets	$	373,016	$	319,013		$	2		$	397,517			$	1,089,548
Liabilities
Risk management activities — derivative instruments:
Commodity contracts	$	—	$	(52,696	)	$	(8,216	)	$	875		(a)	$	(60,037	)

(a) Represents counterparty netting, margin, and collateral. See Note 17.

(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.

Information regarding the entity's internally developed significant unobservable inputs used to value its level 3 instruments

The following tables provide information regarding our significant unobservable inputs used to value our risk management derivative Level 3 instruments at December 31, 2019 and December 31, 2018:

	December 31, 2019 Fair Value (thousands)				Valuation Technique	Significant Unobservable Input	Range	Weighted-Average
Commodity Contracts	Assets		Liabilities
Electricity:
Forward Contracts (a)	$	33	$	819	Discounted cash flows	Electricity forward price (per MWh)	$22.18 - $22.18	$	22.18
Natural Gas:
Forward Contracts (a)	—		2,610		Discounted cash flows	Natural gas forward price (per MMBtu)	$2.33 -$ 2.78	$	2.49
Total	$	33	$	3,429

(a) Includes swaps and physical and financial contracts.

	December 31, 2018 Fair Value (thousands)				Valuation Technique	Significant Unobservable Input	Range	Weighted-Average
Commodity Contracts	Assets		Liabilities
Electricity:
Forward Contracts (a)	$	—	$	2,456	Discounted cash flows	Electricity forward price (per MWh)	$17.88 - $37.03	$	26.10
Natural Gas:
Forward Contracts (a)	2		5,760		Discounted cash flows	Natural gas forward price (per MMBtu)	$1.79 - $2.92	$	2.48
Total	$	2	$	8,216

(a) Includes swaps and physical and financial contracts.

Changes in fair value for assets and liabilities that are measured at fair value on a recurring basis using Level 3 inputs

The following table shows the changes in fair value for our risk management activities' assets and liabilities that are measured at fair value on a recurring basis using Level 3 inputs for the years ended December 31, 2019 and 2018 (dollars in thousands):

	Year Ended December 31,
Commodity Contracts	2019			2018
Net derivative balance at beginning of period	$	(8,214	)	$	(18,256	)
Total net gains (losses) realized/unrealized:
Included in earnings	—			—
Included in OCI	—			—
Deferred as a regulatory asset or liability	(13,457		)	(1,130		)
Settlements	12,250			(787		)
Transfers into Level 3 from Level 2	(6,512		)	(12,830		)
Transfers from Level 3 into Level 2	12,537			24,789
Net derivative balance at end of period	$	(3,396	)	$	(8,214	)
Net unrealized gains included in earnings related to instruments still held at end of period	$	—		$	—