Fair Value (Tables)

6 Months Ended

Jun. 30, 2017

Fair Value Inputs, Liabilities, Quantitative Information [Line Items]

Fair Value Inputs, Liabilities, Quantitative Information [Table Text Block]

The following table presents the quantitative information which was used to estimate the fair values of the Level 3 assets and liabilities above as of June 30, 2017 (dollars in thousands):

	Fair Value (Net) at
	June 30, 2017			Valuation Technique	Unobservable Input	Range
Power exchange agreement	$	(13,784	)	Surrogate facility pricing	O&M charges	$33.59-$49.15/MWh (1)
					Escalation factor	3% - 2017 to 2019
					Transaction volumes	396,984 MWhs
Power option agreement	$	(43	)	Black-Scholes- Merton	Strike price	$35.92/MWh - 2019
						$48.39/MWh - 2018
					Delivery volumes	128,611 - 254,363 MWhs
Natural gas exchange agreement	$	(4,173	)	Internally derived weighted average cost of gas	Forward purchase prices	$1.66 - $2.38/mmBTU
					Forward sales prices	$1.67 - $3.29/mmBTU
					Purchase volumes	115,000 - 310,000 mmBTUs
					Sales volumes	60,000 - 310,000 mmBTUs

Carrying Value and Estimated Fair Value of Financial Instruments

The following table sets forth the carrying value and estimated fair value of the Company’s financial instruments not reported at estimated fair value on the Condensed Consolidated Balance Sheets as of June 30, 2017 and December 31, 2016 (dollars in thousands):

	June 30, 2017				December 31, 2016
	Carrying Value		Estimated Fair Value		Carrying Value		Estimated Fair Value
Long-term debt (Level 2)	$	951,000	$	1,076,925	$	951,000	$	1,048,661
Long-term debt (Level 3)	677,000		701,924		677,000		675,251
Snettisham capital lease obligation (Level 3)	60,953		62,600		62,160		62,800
Long-term debt to affiliated trusts (Level 3)	51,547		43,042		51,547		38,660

Fair Value of Assets And Liabilities Measured on Recurring Basis

	Level 1		Level 2		Level 3		Counterparty and Cash Collateral Netting (1)			Total
June 30, 2017
Assets:
Energy commodity derivatives	$	—	$	35,198	$	—	$	(35,041	)	$	157
Level 3 energy commodity derivatives:
Natural gas exchange agreement	—		—		79		(79		)	—
Foreign currency exchange derivatives	—		187		—		—			187
Interest rate swap derivatives	—		11,302		—		(1,853		)	9,449
Deferred compensation assets:
Fixed income securities (2)	1,716		—		—		—			1,716
Equity securities (2)	6,067		—		—		—			6,067
Total	$	7,783	$	46,687	$	79	$	(36,973	)	$	17,576
Liabilities:
Energy commodity derivatives	$	—	$	46,203	$	—	$	(44,808	)	$	1,395
Level 3 energy commodity derivatives:
Natural gas exchange agreement	—		—		4,252		(79		)	4,173
Power exchange agreement	—		—		13,784		—			13,784
Power option agreement	—		—		43		—			43
Interest rate swap derivatives	—		80,266		—		(43,423		)	36,843
Total	$	—	$	126,469	$	18,079	$	(88,310	)	$	56,238

	Level 1		Level 2		Level 3		Counterparty and Cash Collateral Netting (1)			Total
December 31, 2016
Assets:
Energy commodity derivatives	$	—	$	47,994	$	—	$	(46,099	)	$	1,895
Level 3 energy commodity derivatives:
Natural gas exchange agreement	—		—		69		(69		)	—
Power exchange agreement	—		—		25		(25		)	—
Foreign currency exchange derivatives	—		5		—		(5		)	—
Interest rate swap derivatives	—		13,098		—		(4,348		)	8,750
Deferred compensation assets:
Fixed income securities (2)	1,789		—		—		—			1,789
Equity securities (2)	5,481		—		—		—			5,481
Total	$	7,270	$	61,097	$	94	$	(50,546	)	$	17,915
Liabilities:
Energy commodity derivatives	$	—	$	56,871	$	—	$	(55,957	)	$	914
Level 3 energy commodity derivatives:
Natural gas exchange agreement	—		—		5,954		(69		)	5,885
Power exchange agreement	—		—		13,474		(25		)	13,449
Power option agreement	—		—		76		—			76
Foreign currency exchange derivatives	—		28		—		(5		)	23
Interest rate swap derivatives	—		73,978		—		(39,248		)	34,730
Total	$	—	$	130,877	$	19,504	$	(95,304	)	$	55,077

(1) The Company is permitted to net derivative assets and derivative liabilities with the same counterparty when a legally enforceable master netting agreement exists. In addition, the Company nets derivative assets and derivative liabilities against any payables and receivables for cash collateral held or placed with these same counterparties.

(2) These assets are trading securities and are included in other property and investments-net and other non-current assets on the Condensed Consolidated Balance Sheets.

Reconciliation for All Assets Measured At Fair Value on a Recurring Basis Using Significant Unobservable Inputs (Level 3)

	Natural Gas Exchange Agreement			Power Exchange Agreement			Power Option Agreement			Total
Three months ended June 30, 2017:
Balance as of April 1, 2017	$	(4,278	)	$	(14,419	)	$	(266	)	$	(18,963	)
Total gains or (losses) (realized/unrealized):
Included in regulatory assets/liabilities (1)	(195		)	(672		)	223			(644		)
Settlements	300			1,307			—			1,607
Ending balance as of June 30, 2017 (2)	$	(4,173	)	$	(13,784	)	$	(43	)	$	(18,000	)
Three months ended June 30, 2016:
Balance as of April 1, 2016	$	(6,006	)	$	(20,193	)	$	(97	)	$	(26,296	)
Total gains or (losses) (realized/unrealized):
Included in regulatory assets/liabilities (1)	(1,551		)	4,400			(8		)	2,841
Settlements	700			1,179			—			1,879
Ending balance as of June 30, 2016 (2)	$	(6,857	)	$	(14,614	)	$	(105	)	$	(21,576	)
Six months ended June 30, 2017:
Balance as of January 1, 2017	$	(5,885	)	$	(13,449	)	$	(76	)	$	(19,410	)
Total gains or (losses) (realized/unrealized):
Included in regulatory assets/liabilities (1)	1,817			(5,165		)	33			(3,315		)
Settlements	(105		)	4,830			—			4,725
Ending balance as of June 30, 2017 (2)	$	(4,173	)	$	(13,784	)	$	(43	)	$	(18,000	)
Six months ended June 30, 2016:
Balance as of January 1, 2016	$	(5,039	)	$	(21,961	)	$	(124	)	$	(27,124	)
Total gains or (losses) (realized/unrealized):
Included in regulatory assets/liabilities (1)	(3,296		)	1,968			19			(1,309		)
Settlements	1,478			5,379			—			6,857
Ending balance as of June 30, 2016 (2)	$	(6,857	)	$	(14,614	)	$	(105	)	$	(21,576	)

(1) All gains and losses are included in other regulatory assets and liabilities. There were no gains and losses included in either net income or other comprehensive income during any of the periods presented in the table above.

(2) There were no purchases, issuances or transfers from other categories of any derivatives instruments during the periods presented in the table above.