Fair Value Measurements (Tables)

9 Months Ended

Sep. 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 September 30, 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	$	—	$	1,388		$	388		$	(959	)	(a)	$	817
Nuclear decommissioning trust:
Equity securities	8,774		—			—			(1,322		)	(b)	7,452
U.S. commingled equity funds	—		—			—			476,693			(c)	476,693
U.S. Treasury debt	162,092		—			—			—				162,092
Corporate debt	—		124,026			—			—				124,026
Mortgage-backed securities	—		112,704			—			—				112,704
Municipal bonds	—		74,202			—			—				74,202
Other fixed income	—		10,504			—			—				10,504
Subtotal nuclear decommissioning trust	170,866		321,436			—			475,371				967,673
Other special use funds:
Equity securities	1,982		—			—			1,418			(b)	3,400
U.S. Treasury debt	232,165		—			—			—				232,165
Municipal bonds	—		8,417			—			—				8,417
Subtotal other special use funds	234,147		8,417			—			1,418				243,982
Total assets	$	405,013	$	331,241		$	388		$	475,830			$	1,212,472
Liabilities
Risk management activities — derivative instruments:
Commodity contracts	$	—	$	(69,752	)	$	(1,982	)	$	80		(a)	$	(71,654	)

(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):

	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 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 September 30, 2019 and December 31, 2018:

	September 30, 2019 Fair Value (thousands)				Valuation Technique	Significant Unobservable Input		Weighted-Average
Commodity Contracts	Assets		Liabilities				Range
Electricity:
Forward Contracts (a)	$	388	$	489	Discounted cash flows	Electricity forward price (per MWh)	$17.79 - $17.79	$	17.79
Natural Gas:
Forward Contracts (a)	—		1,493		Discounted cash flows	Natural gas forward price (per MMBtu)	$2.53 - $2.79	$	2.64
Total	$	388	$	1,982

(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 nine months ended September 30, 2019 and 2018 (dollars in thousands):

	Three Months Ended September 30,						Nine Months Ended September 30,
Commodity Contracts	2019			2018			2019			2018
Net derivative balance at beginning of period	$	(12,753	)	$	(9,358	)	$	(8,214	)	$	(18,256	)
Total net gains (losses) realized/unrealized:
Deferred as a regulatory asset or liability	(2,324		)	1,244			(12,634		)	(2,067		)
Settlements	8,980			(2,332		)	11,929			(1,056		)
Transfers into Level 3 from Level 2	(613		)	(2,246		)	(3,711		)	(7,225		)
Transfers from Level 3 into Level 2	5,116			2,829			11,036			18,741
Net derivative balance at end of period	$	(1,594	)	$	(9,863	)	$	(1,594	)	$	(9,863	)
Net unrealized gains included in earnings related to instruments still held at end of period	$	—		$	—		$	—		$	—