Financial Instruments And Investments (Tables)

3 Months Ended

Mar. 31, 2017

Fair Value Disclosures [Abstract]

Fair Values Of Long-Term Debt And Short-Term Borrowings Under the RCF

The fair values of the Company's long-term debt and short-term borrowings under the RCF are based on estimated market prices for similar issues and are presented below (in thousands):

	March 31, 2017				December 31, 2016
	Carrying Amount		Estimated Fair Value		Carrying Amount		Estimated Fair Value
Pollution Control Bonds	$	190,844	$	204,599	$	190,775	$	206,818
Senior Notes	993,170		1,126,625		993,086		1,112,285
RGRT Senior Notes (1)	94,822		98,555		94,795		98,855
RCF (1)	134,178		134,178		81,574		81,574
Total	$	1,413,014	$	1,563,957	$	1,360,230	$	1,499,532

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(1) Nuclear fuel financing, as of March 31, 2017 and December 31, 2016, is funded through the $95 million Rio Grande Resources Trust ("RGRT") Senior Notes and $40.2 million and $37.6 million, respectively under the RCF. As of March 31, 2017, $94.0 million was outstanding under the RCF for working capital or general corporate purposes. As of December 31, 2016, $44.0 million was outstanding under the RCF for working capital or general corporate purposes. The interest rate on the Company's borrowings under the RCF is reset throughout the quarter reflecting current market rates. Consequently, the carrying value approximates fair value.

Unrecognized Gross Unrealized Gains (Losses) And the Fair Value

The tables below present the gross unrealized losses and the fair value of these securities, aggregated by investment category and length of time that individual securities have been in a continuous unrealized loss position (in thousands):

	March 31, 2017
	Less than 12 Months					12 Months or Longer					Total
	Fair Value		Unrealized Losses			Fair Value		Unrealized Losses			Fair Value		Unrealized Losses
Description of Securities (1):
Federal Agency Mortgage Backed Securities	$	11,142	$	(249	)	$	424	$	(23	)	$	11,566	$	(272	)
U.S. Government Bonds	32,621		(739		)	9,876		(570		)	42,497		(1,309		)
Municipal Obligations	9,152		(298		)	4,413		(385		)	13,565		(683		)
Corporate Obligations	9,665		(131		)	2,491		(208		)	12,156		(339		)
Total Debt Securities	62,580		(1,417		)	17,204		(1,186		)	79,784		(2,603		)
Common Stock	541		(53		)	—		—			541		(53		)
Total Temporarily Impaired Securities	$	63,121	$	(1,470	)	$	17,204	$	(1,186	)	$	80,325	$	(2,656	)

_________________

(1) Includes 139 securities.

	December 31, 2016
	Less than 12 Months					12 Months or Longer					Total
	Fair Value		Unrealized Losses			Fair Value		Unrealized Losses			Fair Value		Unrealized Losses
Description of Securities (2):
Federal Agency Mortgage Backed Securities	$	11,582	$	(239	)	$	436	$	(22	)	$	12,018	$	(261	)
U.S. Government Bonds	31,655		(762		)	17,976		(835		)	49,631		(1,597		)
Municipal Obligations	9,596		(394		)	4,067		(372		)	13,663		(766		)
Corporate Obligations	7,971		(172		)	2,092		(172		)	10,063		(344		)
Total Debt Securities	60,804		(1,567		)	24,571		(1,401		)	85,375		(2,968		)
Common Stock	2,760		(167		)	—		—			2,760		(167		)
Institutional Equity Funds-International Equity	22,945		(110		)	—		—			22,945		(110		)
Total Temporarily Impaired Securities	$	86,509	$	(1,844	)	$	24,571	$	(1,401	)	$	111,080	$	(3,245	)

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(2) Includes 152 securities.

Unrealized Holding Losses Included In Pre-Tax Income

For the three and twelve months ended March 31, 2017 and 2016, the Company recognized other than temporary impairment losses on its available-for-sale securities as follow (in thousands):

	Three Months Ended					Twelve Months Ended
	March 31,					March 31,
	2017		2016			2017			2016
Unrealized holding losses included in pre-tax income	$	—	$	(156	)	$	(196	)	$	(494	)

Marketable Securities Fair Value and Unrecognized Gross Unrealized Gain

The table below presents the unrecognized gross unrealized gains and the fair value of these securities, aggregated by investment category (in thousands): 

	March 31, 2017				December 31, 2016
	Fair Value		Unrealized Gains		Fair Value		Unrealized Gains
Description of Securities:
Federal Agency Mortgage Backed Securities	$	6,991	$	276	$	7,430	$	319
U.S. Government Bonds	15,811		198		12,237		138
Municipal Obligations	4,086		144		2,481		144
Corporate Obligations	14,393		710		12,350		655
Total Debt Securities	41,281		1,328		34,498		1,256
Common Stock	62,487		34,868		61,884		34,066
Equity Mutual Funds	50,225		5,690		42,244		3,345
Institutional Funds - International Equity	24,737		1,722		—		—
Cash and Cash Equivalents	6,802		—		6,002		—
Total	$	185,532	$	43,608	$	144,628	$	38,667

Contractual Year For Maturity Of Available-For-Sale Securities

The contractual year for maturity of these available-for-sale securities as of March 31, 2017 is as follows (in thousands):

	Total		2017		2018 through 2021		2022 through 2026		2027 and Beyond
Municipal Debt Obligations	$	17,651	$	804	$	6,366	$	9,203	$	1,278
Corporate Debt Obligations	26,549		—		10,110		7,511		8,928
U.S. Government Bonds	58,308		5,928		27,123		14,834		10,423
Federal Agency Mortgage Backed Securities	18,557		—		6		356		18,195

Sale of Securities And The Related Effects On Pre-Tax Income

The proceeds from the sale of these securities during the three and twelve months ended March 31, 2017 and 2016 and the related effects on pre-tax income are as follows (in thousands):

	Three Months Ended						Twelve Months Ended
	March 31,						March 31,
	2017			2016			2017			2016
Proceeds from sales or maturities of available-for-sale securities	$	26,055		$	24,078		$	93,245		$	102,003
Gross realized gains included in pre-tax income	$	2,587		$	1,832		$	9,968		$	10,429
Gross realized losses included in pre-tax income	(396		)	(288		)	(1,329		)	(1,178		)
Gross unrealized losses included in pre-tax income	—			(156		)	(196		)	(494		)
Net gains included in pre-tax income	$	2,191		$	1,388		$	8,443		$	8,757
Net unrealized holding gains (losses) included in accumulated other comprehensive income	$	7,721		$	2,190		$	13,975		$	(1,730	)
Net gains reclassified from accumulated other comprehensive income	(2,191		)	(1,388		)	(8,443		)	(8,757		)
Net gains (losses) in other comprehensive income	$	5,530		$	802		$	5,532		$	(10,487	)

Fair Value, Measurement Inputs, Disclosure

The fair value of the Company's decommissioning trust funds and investments in debt securities at March 31, 2017 and December 31, 2016, and the level within the three levels of the fair value hierarchy defined by the FASB guidance are presented in the table below (in thousands):

Description of Securities	Fair Value as of March 31, 2017		Quoted Prices in Active Markets for Identical Assets (Level 1)		Significant Other Observable Inputs (Level 2)		Significant Unobservable Inputs (Level 3)
Trading Securities:
Investments in Debt Securities	$	1,628	$	—	$	—	$	1,628
Available for sale:
U.S. Government Bonds	$	58,308	$	58,308	$	—	$	—
Federal Agency Mortgage Backed Securities	18,557		—		18,557		—
Municipal Obligations	17,651		—		17,651		—
Corporate Obligations	26,549		—		26,549		—
Subtotal, Debt Securities	121,065		58,308		62,757		—
Common Stock	63,028		63,028		—		—
Equity Mutual Funds	50,225		50,225		—		—
Institutional Funds-International Equity	24,737		24,737		—		—
Cash and Cash Equivalents	6,802		6,802		—		—
Total Available for Sale	$	265,857	$	203,100	$	62,757	$	—

Description of Securities	Fair Value as of December 31, 2016		Quoted Prices in Active Markets for Identical Assets (Level 1)		Significant Other Observable Inputs (Level 2)		Significant Unobservable Inputs (Level 3)
Trading Securities:
Investments in Debt Securities	$	1,421	$	—	$	—	$	1,421
Available for sale:
U.S. Government Bonds	$	61,868	$	61,868	$	—	$	—
Federal Agency Mortgage Backed Securities	19,448		—		19,448		—
Municipal Obligations	16,144		—		16,144		—
Corporate Obligations	22,413		—		22,413		—
Subtotal, Debt Securities	119,873		61,868		58,005		—
Common Stock	64,644		64,644		—		—
Equity Mutual Funds	42,244		42,244		—		—
Institutional Funds-International Equity	22,945		22,945		—		—
Cash and Cash Equivalents	6,002		6,002		—		—
Total Available for Sale	$	255,708	$	197,703	$	58,005	$	—