Fair Value Measurements (Tables)

6 Months Ended

Jun. 30, 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 June 30, 2019 of our assets and liabilities that are measured at fair value on a recurring basis (dollars in thousands):

	Quoted Prices in Active Markets for Identical Assets (Level 1)		Significant Other Observable Inputs (Level 2)			Significant Unobservable Inputs (Level 3)			Other				Balance at June 30, 2019
Assets
Risk management activities — derivative instruments:
Commodity contracts	$	—	$	3,198		$	436		$	(3,099	)	(a)	$	535
Nuclear decommissioning trust:
Equity securities	5,319		—			—			6,665			(b)	11,984
U.S. commingled equity funds	—		—			—			469,375			(c)	469,375
U.S. Treasury debt	162,044		—			—			—				162,044
Corporate debt	—		115,674			—			—				115,674
Mortgage-backed securities	—		113,179			—			—				113,179
Municipal bonds	—		67,158			—			—				67,158
Other fixed income	—		11,034			—			—				11,034
Subtotal nuclear decommissioning trust	167,363		307,045			—			476,040				950,448
Other special use funds:
Equity securities	13,200		—			—			997			(b)	14,197
U.S. Treasury debt	214,712		—			—			—				214,712
Municipal bonds	—		12,649			—			—				12,649
Subtotal other special use funds	227,912		12,649			—			997				241,558
Total assets	$	395,275	$	322,892		$	436		$	473,938			$	1,192,541
Liabilities
Risk management activities — derivative instruments:
Commodity contracts	$	—	$	(68,992	)	$	(13,189	)	$	1,755		(a)	$	(80,426	)

(a) Represents counterparty netting, margin, and collateral. See Note 7.

(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):

	Quoted Prices in Active Markets for Identical Assets (Level 1)		Significant Other Observable Inputs (Level 2)			Significant Unobservable Inputs (Level 3)			Other				Balance at December 31, 2018
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 7.

(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 June 30, 2019 and December 31, 2018:

	June 30, 2019 Fair Value (thousands)				Valuation Technique	Significant Unobservable Input		Weighted-Average
Commodity Contracts	Assets		Liabilities				Range
Electricity:
Forward Contracts (a)	$	294	$	11,675	Discounted cash flows	Electricity forward price (per MWh)	$18.27 - $30.11	$	26.78
Natural Gas:
Forward Contracts (a)	142		1,514		Discounted cash flows	Natural gas forward price (per MMBtu)	$0.05 - $2.88	$	2.41
Total	$	436	$	13,189

(a) Includes swaps and physical and financial contracts.

	December 31, 2018 Fair Value (thousands)				Valuation Technique	Significant Unobservable Input		Weighted-Average
Commodity Contracts	Assets		Liabilities				Range
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 three and six months ended June 30, 2019 and 2018 (dollars in thousands):

	Three Months Ended June 30,						Six Months Ended June 30,
Commodity Contracts	2019			2018			2019			2018
Net derivative balance at beginning of period	$	(5,612	)	$	(19,754	)	$	(8,214	)	$	(18,256	)
Total net gains (losses) realized/unrealized:
Deferred as a regulatory asset or liability	(8,731		)	(989		)	(10,310		)	(3,311		)
Settlements	2,431			494			2,949			1,276
Transfers into Level 3 from Level 2	(3,096		)	(2,534		)	(3,098		)	(4,979		)
Transfers from Level 3 into Level 2	2,255			13,425			5,920			15,912
Net derivative balance at end of period	$	(12,753	)	$	(9,358	)	$	(12,753	)	$	(9,358	)
Net unrealized gains included in earnings related to instruments still held at end of period	$	—		$	—		$	—		$	—