Financial Instruments And Investments (Tables)

3 Months Ended

Mar. 31, 2018

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, 2018				December 31, 2017
	Carrying Amount		Estimated Fair Value		Carrying Amount		Estimated Fair Value
Pollution Control Bonds	$	157,699	$	166,779	$	157,676	$	169,186
Senior Notes	993,514		1,147,504		993,426		1,211,922
RGRT Senior Notes (1)	44,897		46,620		44,886		47,070
RCF (1)	233,067		233,067		173,533		173,533
Total	$	1,429,177	$	1,593,970	$	1,369,521	$	1,601,711

_______________

(1) Nuclear fuel financing, as of March 31, 2018 and December 31, 2017, is funded through $45 million Rio Grande Resources Trust ("RGRT") Senior Notes and $89.1 million and $88.5 million, respectively, under the RCF. As of March 31, 2018 and December 31, 2017, $144.0 million and $85.0 million, respectively, 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, 2018
	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	$	5,995	$	(114	)	$	10,376	$	(407	)	$	16,371	$	(521	)
U.S. Government Bonds	34,018		(940		)	18,325		(1,215		)	52,343		(2,155		)
Municipal Debt Obligations	4,227		(109		)	7,031		(581		)	11,258		(690		)
Corporate Debt Obligations	20,855		(609		)	3,769		(301		)	24,624		(910		)
Total	$	65,095	$	(1,772	)	$	39,501	$	(2,504	)	$	104,596	$	(4,276	)

_________________

(1) Includes 147 securities.

	December 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 (2):
Federal Agency Mortgage Backed Securities	$	4,700	$	(46	)	$	10,099	$	(165	)	$	14,799	$	(211	)
U.S. Government Bonds	28,866		(416		)	18,186		(969		)	47,052		(1,385		)
Municipal Debt Obligations	4,290		(73		)	9,736		(742		)	14,026		(815		)
Corporate Debt Obligations	10,685		(107		)	4,475		(331		)	15,160		(438		)
Total Debt Securities	48,541		(642		)	42,496		(2,207		)	91,037		(2,849		)
Domestic Equity Securities	962		(210		)	—		—			962		(210		)
Total	$	49,503	$	(852	)	$	42,496	$	(2,207	)	$	91,999	$	(3,059	)

_________________

(2) Includes 146 securities.

Unrealized Holding Losses Included In Pre-Tax Income

For the three and twelve months ended March 31, 2018 and 2017, the Company recognized other than temporary impairment losses on its available-for-sale securities as follows (in thousands):

	Three Months Ended				Twelve Months Ended
	March 31,				March 31,
	2018		2017		2018		2017
Unrealized holding losses included in pre-tax income	$	—	$	—	$	—	$	(196	)

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, 2018				December 31, 2017
	Fair Value		Unrealized Gains		Fair Value		Unrealized Gains
Description of Securities:
Federal Agency Mortgage Backed Securities	$	9,469	$	143	$	5,933	$	203
U.S. Government Bonds	2,205		92		11,129		256
Municipal Debt Obligations	1,073		92		2,558		109
Corporate Debt Obligations	11,444		546		19,514		1,067
Total Debt Securities	24,191		873		39,134		1,635
Domestic Equity Securities	—		—		120,065		45,587
International Equity Securities	—		—		28,804		5,908
Cash and Cash Equivalents	—		—		6,864		—
Total	$	24,191	$	873	$	194,867	$	53,130

Contractual Year For Maturity Of Available-For-Sale Securities

The contractual year for maturity of these available-for-sale debt securities as of March 31, 2018, is as follows (in thousands):

	Total		2018		2019 through 2022		2023 through 2027		2028 and Beyond
Federal Agency Mortgage Backed Securities	$	25,840	$	—	$	16	$	261	$	25,563
U.S. Government Bonds	54,548		1,894		28,263		11,415		12,976
Municipal Debt Obligations	12,331		76		5,483		5,735		1,037
Corporate Debt Obligations	36,068		213		17,518		7,151		11,186

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, 2018 and 2017, and the related effects on pre-tax income are as follows (in thousands):

	Three Months Ended						Twelve Months Ended
	March 31,						March 31,
	2018			2017			2018			2017
Proceeds from sales or maturities of available-for-sale securities	$	11,757		$	26,055		$	82,739		$	93,245
Gross realized gains included in pre-tax income	$	9		$	2,587		$	9,195		$	9,968
Gross realized losses included in pre-tax income	(527		)	(396		)	(1,278		)	(1,329		)
Gross unrealized losses included in pre-tax income	—			—			—			(196		)
Net gains included in pre-tax income	$	(518	)	$	2,191		$	7,917		$	8,443

Unrealized Gain (Loss) on Investments

The unrealized gains and losses recognized during the three months ended March 31, 2018 and related effects on pre-tax income are as follows (in thousands):

	Three Months Ended
	March 31, 2018
Net gains and (losses) recognized on equity securities	$	(1,991	)
Less: Net gains and (losses) recognized on equity securities sold	1,790
Unrealized gains and (losses) recognized on equity securities still held at reporting date	$	(3,781	)

Fair Value, Measurement Inputs, Disclosure

The fair value of the NDT and investments in debt securities at March 31, 2018 and December 31, 2017, 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, 2018		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	$	1,726	$	—	$	—	$	1,726
Equity Securities:
Domestic	$	119,344	$	119,344	$	—	$	—
International	28,542		28,542		—		—
Total Equity Securities	147,886		147,886		—		—
Available for Sale Debt Securities:
Federal Agency Mortgage Backed Securities	25,840		—		25,840		—
U.S. Government Bonds	54,548		54,548		—		—
Municipal Debt Obligations	12,331		—		12,331		—
Corporate Debt Obligations	36,068		—		36,068		—
Total Available for Sale Debt Securities	128,787		54,548		74,239		—
Cash and Cash Equivalents	7,409		7,409		—		—
Total	$	284,082	$	209,843	$	74,239	$	—

Description of Securities	Fair Value as of December 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	$	1,735	$	—	$	—	$	1,735
Available for Sale:
Federal Agency Mortgage Backed Securities	$	20,732	$	—	$	20,732	$	—
U.S. Government Bonds	58,181		58,181		—		—
Municipal Debt Obligations	16,584		—		16,584		—
Corporate Debt Obligations	34,674		—		34,674		—
Subtotal, Debt Securities	130,171		58,181		71,990		—
Domestic	121,027		121,027		—		—
International	28,804		28,804		—		—
Subtotal, Equity Securities	149,831		149,831		—		—
Cash and Cash Equivalents	6,864		6,864		—		—
Total	$	286,866	$	214,876	$	71,990	$	—