El Paso Electric 10-Q 8 May 14 2014 Q1 Quarterly report Financial data

Document_And_Entity_Informatio

Document And Entity Information	3 Months Ended
	Mar. 31, 2014	Apr. 30, 2014
Document and Entity Information [Line Items]	'	'
Document Type	'10-Q	'
Amendment Flag	'false	'
Document Period End Date	31-Mar-14	'
Document Fiscal Year Focus	'2014	'
Document Fiscal Period Focus	'Q1	'
Trading Symbol	'ee	'
Entity Registrant Name	'EL PASO ELECTRIC CO /TX/	'
Entity Central Index Key	'0000031978	'
Current Fiscal Year End Date	'--12-31	'
Entity Filer Category	'Large Accelerated Filer	'
Entity Common Stock, Shares Outstanding	'	40,310,281

Balance_Sheets

Balance Sheets (USD $)	Mar. 31, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Utility plant:	'	'
Electric plant in service	$3,086,015	$3,076,549
Less accumulated depreciation and amortization	-1,219,479	-1,214,088
Net plant in service	1,866,536	1,862,461
Construction work in progress	304,619	282,647
Nuclear fuel; includes fuel in process of $39,681 and $48,492, respectively	200,454	188,185
Less accumulated amortization	-86,461	-75,820
Net nuclear fuel	113,993	112,365
Net utility plant	2,285,148	2,257,473
Current assets:	'	'
Cash and cash equivalents	13,392	25,592
Accounts receivable, principally trade, net of allowance for doubtful accounts of $1,828 and $2,261, respectively	58,750	65,350
Accumulated deferred income taxes	23,972	26,965
Inventories, at cost	45,300	45,942
Undercollection of fuel revenues	4,189	7,248
Prepayments and other	10,501	7,694
Total current assets	156,104	178,791
Deferred charges and other assets:	'	'
Decommissioning trust funds	217,509	214,095
Regulatory assets	96,603	101,050
Other	36,409	34,879
Total deferred charges and other assets	350,521	350,024
Total assets	2,791,773	2,786,288
Capitalization:	'	'
Common stock, stated value $1 per share, 100,000,000 shares authorized, 65,642,538 and 65,639,091 shares issued, and 154,144 and 120,534 restricted shares, respectively	65,797	65,760
Capital in excess of stated value	315,177	314,443
Retained earnings	979,604	985,665
Accumulated other comprehensive income, net of tax	13,059	2,612
Total stockholders equity subtotal before treasury stock	1,373,637	1,368,480
Treasury stock, 25,492,919 shares at cost	-424,647	-424,647
Common stock equity	948,990	943,833
Long-term debt	999,643	999,620
Total capitalization	1,948,633	1,943,453
Current liabilities:	'	'
Short-term borrowings under the revolving credit facility	45,951	14,352
Accounts payable, principally trade	46,597	61,795
Taxes accrued	22,107	25,206
Interest accrued	13,028	12,189
Overcollection of fuel revenues	0	1,048
Other	23,766	22,932
Total current liabilities	151,449	137,522
Deferred Credits and Other Liabilities:	'	'
Accumulated deferred income taxes	455,535	449,925
Accrued pension liability	62,212	84,012
Accrued postretirement benefit liability	51,954	50,655
Asset retirement obligation	66,665	65,214
Regulatory liabilities	25,969	26,416
Other	29,356	29,091
Total deferred credits and other liabilities	691,691	705,313
Commitments and contingencies	'	'
Total capitalization and liabilities	$2,791,773	$2,786,288

Balance_Sheets_Parenthetical

Balance Sheets Parenthetical (USD $)	Mar. 31, 2014	Dec. 31, 2013
In Thousands, except Share data, unless otherwise specified
Nuclear fuel; fuel in process	$39,681	$48,492
Allowance for Doubtful Accounts Receivable, Current	$1,828	$2,261
Common Stock, Par or Stated Value Per Share	$1	$1
Common Stock, Shares Authorized	100,000,000	100,000,000
Common Stock, Shares, Issued	65,642,538	65,639,091
Common stock, restricted shares	154,144	120,534
Treasury Stock, Shares	25,492,919	25,492,919

Statements_Of_Operations

Statements Of Operations (USD $)	3 Months Ended		12 Months Ended
In Thousands, except Share data, unless otherwise specified	Mar. 31, 2014	Mar. 31, 2013	Mar. 31, 2014	Mar. 31, 2013
Operating revenues	$185,516	$177,290	$898,588	$861,593
Energy expenses:	'	'	'	'
Fuel	51,586	44,399	233,955	196,041
Purchased and interchanged power	17,915	12,877	67,401	60,569
Cost of services, energy services	69,501	57,276	301,356	256,610
Operating revenues net of energy expenses	116,015	120,014	597,232	604,983
Other operating expenses:	'	'	'	'
Other operations	56,138	55,967	237,326	238,108
Maintenance	14,282	12,552	62,798	56,923
Depreciation and amortization	20,568	19,368	80,826	77,406
Taxes other than income taxes	15,362	12,782	60,327	56,585
Utilities operating expense	106,350	100,669	441,277	429,022
Operating income	9,665	19,345	155,955	175,961
Other income (deductions):	'	'	'	'
Allowance for equity funds used during construction	2,906	2,663	10,251	10,134
Investment and interest income, net	4,241	1,231	10,043	4,730
Miscellaneous non-operating income	1,517	1	2,425	1,346
Miscellaneous non-operating deductions	-419	-471	-3,583	-2,002
Nonoperating income (expense)	8,245	3,424	19,136	14,208
Interest charges (credits):	'	'	'	'
Interest on long-term debt and revolving credit facility	14,579	14,596	58,618	55,665
Other interest	173	149	455	1,139
Capitalized interest	-1,246	-1,302	-5,243	-5,245
Allowance for borrowed funds used during construction	-1,684	-1,623	-6,116	-6,043
Interest expense	11,822	11,820	47,714	45,516
Income before income taxes	6,088	10,949	127,377	144,653
Income tax expense	1,473	3,315	41,813	49,517
Net income	$4,615	$7,634	$85,564	$95,136
Basic earnings per share	$0.11	$0.19	$2.13	$2.37
Diluted earnings per share	$0.11	$0.19	$2.12	$2.37
Dividends declared per share of common stock	$0.27	$0.25	$1.06	$1
Weighted average number of shares outstanding	40,149,083	40,078,061	40,132,106	40,015,380
Weighted average number of shares and dilutive potential shares outstanding	40,149,083	40,078,061	40,144,159	40,074,820

Statements_Of_Comprehensive_Op

Statements Of Comprehensive Operations (USD $)	3 Months Ended		12 Months Ended
In Thousands, unless otherwise specified	Mar. 31, 2014	Mar. 31, 2013	Mar. 31, 2014	Mar. 31, 2013
Net income	$4,615	$7,634	$85,564	$95,136
Unrecognized pension and postretirement benefit costs:	'	'	'	'
Net gain (loss) arising during period	19,700	0	102,664	-2,109
Prior service benefit	0	0	97	0
Reclassification adjustments included in net income for amortization of:	'	'	'	'
Prior service benefit	-1,459	-1,400	-5,619	-5,719
Net loss	1,123	2,675	8,920	11,521
Net unrealized gains/losses on marketable securities:	'	'	'	'
Net holding gains arising during period	998	6,793	11,904	8,562
Reclassification adjustments for net (gains) losses included in net income	-2,865	158	-3,576	1,413
Net losses on cash flow hedges:	'	'	'	'
Reclassification adjustment for interest expense included in net income	107	101	417	392
Total other comprehensive income before income taxes	17,604	8,327	114,807	14,060
Income tax benefit (expense) related to items of other comprehensive income (loss):	'	'	'	'
Unrecognized pension and postretirement benefit costs	-7,422	-570	-40,418	-1,479
Net unrealized losses (gains) on marketable securities	357	-1,287	-1,456	-2,166
Losses on cash flow hedges	-92	-52	-208	-138
Total income tax expense	-7,157	-1,909	-42,082	-3,783
Other comprehensive income, net of tax	10,447	6,418	72,725	10,277
Comprehensive income	$15,062	$14,052	$158,289	$105,413

Statements_Of_Cash_Flows

Statements Of Cash Flows (USD $)	3 Months Ended
In Thousands, unless otherwise specified	Mar. 31, 2014	Mar. 31, 2013
Cash flows from operating activities:	'	'
Net income	$4,615	$7,634
Adjustments to reconcile net income to net cash provided by operating activities:	'	'
Depreciation and amortization of electric plant in service	20,568	19,368
Amortization of Nuclear Fuel	11,476	11,510
Deferred income taxes, net	761	3,103
Allowance for equity funds used during construction	-2,906	-2,663
Other amortization and accretion	4,141	4,081
Gain on sale of assets	-1,499	0
Other operating activities	-2,811	179
Change in:	'	'
Accounts receivable	6,600	-3,645
Inventories	525	-1,220
Net overcollection of fuel revenues	2,011	3,844
Prepayments and other	-2,968	-3,519
Accounts payable	-8,958	-18,585
Taxes accrued	-379	-866
Other current liabilities	1,673	2,004
Deferred charges and credits	-1,537	-13,492
Net cash provided by operating activities	31,312	7,733
Cash flows from investing activities:	'	'
Cash additions to utility property, plant and equipment	-48,255	-55,406
Cash additions to nuclear fuel	-11,822	-9,888
Capitalized interest and AFUDC:	'	'
Utility property, plant and equipment	-4,590	-4,286
Nuclear fuel	-1,246	-1,302
Allowance for equity funds used during construction	2,906	2,663
Decommissioning trust funds:	'	'
Purchases, including funding of $1.1 million	-31,242	-13,378
Sales and maturities	28,827	10,907
Proceeds from sale of assets	1,679	0
Other investing activities	375	3,285
Net cash used for investing activities	-63,368	-67,405
Cash flows from financing activities:	'	'
Dividends paid	-10,676	-10,050
Borrowings under the revolving credit facility:	'	'
Proceeds	51,563	12,586
Payments	-19,964	-9,702
Other financing activities	-1,067	-544
Net cash provided by (used for) financing activities	19,856	-7,710
Net decrease in cash and cash equivalents	-12,200	-67,382
Cash and cash equivalents at beginning of period	25,592	111,057
Cash and cash equivalents at end of period	$13,392	$43,675

Statements_Of_Cash_Flows_Paren

Statements Of Cash Flows Parenthetical (USD $)	3 Months Ended
In Millions, unless otherwise specified	Mar. 31, 2014	Mar. 31, 2013
Payments To Fund Decommissioning Fund	$1.10	$1.10

Principles_Of_Preparation

Principles Of Preparation	3 Months Ended
	Mar. 31, 2014
Accounting Policies [Abstract]	'
Principles Of Preparation	'
	Principles of Preparation
	These condensed financial statements should be read in conjunction with the financial statements and notes thereto in the Annual Report of El Paso Electric Company on Form 10-K for the year ended December 31, 2013 (the “2013 Form 10-K”). Capitalized terms used in this report and not defined herein have the meaning ascribed to such terms in the 2013 Form 10-K. In the opinion of the Company’s management, the accompanying financial statements contain all adjustments necessary to present fairly the financial position of the Company at March 31, 2014 and December 31, 2013; the results of its operations and comprehensive operations for the three and twelve months ended March 31, 2014 and 2013; and its cash flows for the three months ended March 31, 2014 and 2013. The results of operations and comprehensive operations and cash flows for the three months ended March 31, 2014 are not necessarily indicative of the results to be expected for the full calendar year.
	Pursuant to the rules and regulations of the Securities and Exchange Commission (“SEC”), certain financial information has been condensed and certain footnote disclosures have been omitted. Such information and disclosures are normally included in financial statements prepared in accordance with generally accepted accounting principles.
	Use of Estimates. The preparation of financial statements in conformity with generally accepted accounting principles requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of the financial statements and the reported amounts of revenues and expenses during the reporting period. Actual results could differ from those estimates.
	Revenues. Revenues related to the sale of electricity are generally recorded when service is rendered or electricity is delivered to customers. The billing of electricity sales to retail customers is based on the reading of their meters, which occurs on a systematic basis throughout the month. Unbilled revenues are estimated based on monthly generation volumes and by applying an average revenue/kWh to the number of estimated kWhs delivered but not billed. Accounts receivable included accrued unbilled revenues of $17.7 million at March 31, 2014 and $19.8 million at December 31, 2013. The Company presents revenues net of sales taxes in its statements of operations.
	Supplemental Cash Flow Disclosures (in thousands)
			Three Months Ended
			March 31,
			2014			2013
	Cash paid (received) for:
		Interest on long-term debt and borrowing under the revolving credit facility	$	10,174		$	9,893
		Income tax refund, net	(767		)	(3,088		)
	Non-cash financing activities:
		Grants of restricted shares of common stock	1,197			929
		Issuance of performance shares	—			849
	New Accounting Standards. In July 2013, the FASB issued new guidance (ASU 2013-11, Income Taxes (Topic 740)) to eliminate the diversity in the financial statement presentation of an unrecognized tax benefit when a net operating loss carryforward, a similar tax loss, or a tax credit carryforward exists. ASU 2013-11 requires an entity to present an unrecognized tax benefit in the financial statements as a reduction to a deferred tax asset for a net operating loss carryforward, a similar tax loss, or a tax credit carryforward, except in certain circumstances when it would be reflected as a liability. ASU 2013-11 is effective prospectively to all unrecognized tax benefits that exist for reporting periods beginning after December 15, 2013 and early adoption is permitted. Retrospective application is also permitted. The Company implemented ASU 2013-11 in the first quarter of 2014 on a prospective basis. This ASU did not have a significant impact on the Company's statement of operations or statement of cash flows.

Accumulated_Other_Comprehensiv

Accumulated Other Comprehensive Income (Notes)	3 Months Ended
	Mar. 31, 2014
Accumulated Other Comprehensive Income (Loss) [Line Items]	'
Comprehensive Income (Loss) Note [Text Block]	'
	Accumulated Other Comprehensive Income (Loss)
	Changes in Accumulated Other Comprehensive Income (Loss) (net of tax) by component which are presented below (in thousands):
			Three Months Ended March 31, 2014																Three Months Ended March 31, 2013
			Unrecognized Pension and Postretirement Benefit Costs				Net Unrealized Gains (Losses) on Marketable Securities				Net Losses on Cash Flow Hedges				Accumulated Other Comprehensive Income (Loss)				Unrecognized Pension and Postretirement Benefit Costs			Net Unrealized Gains (Losses) on Marketable Securities		Net Losses on Cash Flow Hedges			Accumulated Other Comprehensive Income (Loss)
	Balance at beginning of period		$	(21,330	)		$	36,240			$	(12,298	)		$	2,612			$	(75,737	)	$	22,194	$	(12,541	)	$	(66,084	)
		Other comprehensive income before reclassifications	12,147				799				—				12,946				—			5,543		—			5,543
		Amounts reclassified from accumulated other comprehensive income (loss)	(205		)		(2,309		)		15				(2,499		)		705			121		49			875
	Balance at end of period		$	(9,388	)		$	34,730			$	(12,283	)		$	13,059			$	(75,032	)	$	27,858	$	(12,492	)	$	(59,666	)
			Twelve Months Ended March 31, 2014																Twelve Months Ended March 31, 2013
			Unrecognized Pension and Postretirement Benefit Costs				Net Unrealized Gains (Losses) on Marketable Securities				Net Losses on Cash Flow Hedges				Accumulated Other Comprehensive Income (Loss)				Unrecognized Pension and Postretirement Benefit Costs			Net Unrealized Gains (Losses) on Marketable Securities		Net Losses on Cash Flow Hedges			Accumulated Other Comprehensive Income (Loss)
	Balance at beginning of period		$	(75,032	)		$	27,858			$	(12,492	)		$	(59,666	)		$	(77,246	)	$	20,049	$	(12,746	)	$	(69,943	)
		Other comprehensive income (loss) before reclassifications	63,599				9,738				—				73,337				(1,264		)	6,695		—			5,431
		Amounts reclassified from accumulated other comprehensive income (loss)	2,045				(2,866		)		209				(612		)		3,478			1,114		254			4,846
	Balance at end of period		$	(9,388	)		$	34,730			$	(12,283	)		$	13,059			$	(75,032	)	$	27,858	$	(12,492	)	$	(59,666	)
	Amounts reclassified from accumulated other comprehensive income (loss) for the three and twelve months ended March 31, 2014 and 2013 are as follows ( in thousands):
	Details about Accumulated Other Comprehensive Income (Loss) Components			Three Months Ended March 31,								Twelve Months Ended March 31,								Affected Line Item in the Statement of Operations
				2014				2013				2014				2013
	Amortization of pension and postretirement benefit costs:
		Prior service benefit		$	1,459			1,400				$	5,619			$	5,719			(a)
		Net loss		(1,123		)		(2,675		)		(8,920		)		(11,521		)		(a)
				336				(1,275		)		(3,301		)		(5,802		)		(a)
		Income tax effect		(131		)		570				1,256				2,324
				205				(705		)		(2,045		)		(3,478		)		(a)
	Marketable securities:
		Net realized gain (loss) on sale of securities		2,865				(158		)		3,576				(934		)		Investment and interest income, net
		Unrealized losses on available-for-sale securities included in pre-tax income		—				—				—				(479		)		Investment and interest income, net
				2,865				(158		)		3,576				(1,413		)		Income before income taxes
				(556		)		37				(710		)		299				Income tax expense
				2,309				(121		)		2,866				(1,114		)		Net income
	Loss on cash flow hedge:
		Amortization of loss		(107		)		(101		)		(417		)		(392		)		Interest on long-term debt and revolving credit facility
				(107		)		(101		)		(417		)		(392		)		Income before income taxes
				92				52				208				138				Income tax expense
				(15		)		(49		)		(209		)		(254		)		Net income
		Total reclassifications		$	2,499			$	(875	)		$	612			$	(4,846	)
	(a) These items are included in the computation of net periodic benefit cost. See Note H, Employee Benefits, for additional information.

Regulation

Regulation	3 Months Ended
	Mar. 31, 2014
Public Utilities, General Disclosures [Abstract]	'
Regulation	'
	Regulation
	General
	The rates and services of the Company are regulated by incorporated municipalities in Texas, the PUCT, the NMPRC, and the FERC. The PUCT and the NMPRC have jurisdiction to review municipal orders, ordinances and utility agreements regarding rates and services within their respective states and over certain other activities of the Company. The FERC has jurisdiction over the Company's wholesale (sales for resale) transactions, transmission service and compliance with federally-mandated reliability standards. The decisions of the PUCT, NMPRC and the FERC are subject to judicial review.
	Texas Regulatory Matters
	2012 Texas Retail Rate Settlement. On April 17, 2012, the El Paso City Council approved the settlement of the Company's 2012 Texas retail rate case and fuel reconciliation in PUCT Docket No. 40094. The PUCT issued a final order approving the settlement on May 23, 2012 and the rates were effective as of May 1, 2012. As part of the settlement, the Company agreed to submit a future fuel reconciliation request covering the period beginning July 1, 2009 and ending no later than June 30, 2013 by December 31, 2013 or as part of its next rate case, if earlier. The Company filed a fuel reconciliation request covering the period July 1, 2009 through March 31, 2013, as later discussed. The settlement also provided for the continuation of the energy efficiency cost recovery factor and the military base discount recovery factor. Both of these surcharges require annual filings to reconcile and revise the recovery factors.
	Fuel and Purchased Power Costs. The Company's actual fuel costs, including purchased power energy costs, are recovered from customers through a fixed fuel factor. The PUCT has adopted a fuel cost recovery rule ( the "Texas Fuel Rule") that allows the Company to seek periodic adjustments to its fixed fuel factor. The Company can seek to revise its fixed fuel factor based upon the approved formula at least four months after its last revision except in the month of December. On September 9, 2013, the Company filed a request, which was assigned Docket No. 41803, to increase its fixed fuel factor by $16.9 million or 12.2% annually, pursuant to its approved formula. The revised fixed fuel factor reflected increases in prices for natural gas. The increase in the fixed fuel factor was approved on September 23, 2013 and was effective with October 2013 billings. On April 15, 2014, the Company filed a request, which was assigned Docket No. 42384, to increase its fixed fuel factor by $10.7 million or 6.9% annually, pursuant to its approved formula. The revised fixed fuel factor reflects further increases in prices for natural gas. The increase in the fixed fuel factor received interim approval on April 28, 2014 and was effective with May 2014 billings.
	Fuel Reconciliation Proceeding. On September 27, 2013, the Company filed an application with the PUCT, designated as Docket No. 41852, to reconcile $545.3 million of fuel and purchased power expenses incurred during the 45-month period from July 1, 2009 through March 31, 2013. The fuel reconciliation requests to recover $3.4 million of rewards for Palo Verde operations. Hearings in the fuel reconciliation have been suspended as the parties in the case seek to negotiate a settlement. The Company is unable to predict the outcome of these settlement negotiations. A final order must be issued by September 26, 2014.
	Montana Power Station Approvals. The Company has received a Certificate of Convenience and Necessity ("CCN") authorization from the PUCT to construct the first two (of four) units of the Montana Power Station ("the MPS"). The Company also had to obtain air permits from state and federal regulatory agencies before it could begin construction. On January 22, 2014, the Texas Commission on Environmental Quality ("TCEQ") issued the required permit. The U.S. Environmental Protection Agency ("EPA") issued a permit for greenhouse gas ("GHG") on March 25, 2014. This permit became final on April 25, 2014 when no appeals were filed prior to the expiration of the period for appeal.
	On September 6, 2013, the Company filed an application with the PUCT for issuance of a CCN to construct, own and operate two additional 88 MW natural gas-fired generating units designated as the MPS Units 3 and 4 in El Paso County, Texas. The case has been designated PUCT Docket No. 41763. Hearings in this case were held in February 2014. In accordance with PUCT rules, the final order must be issued by September 5, 2014.
	The Company filed three transmission line CCN applications with the PUCT as part of the MPS Project:
	•	MPS to Caliente: a 115-kV transmission line from the MPS to the existing Caliente Substation in east El Paso. (PUCT Docket No. 41360)
	•	MPS In & Out: a 115-kV transmission line from the MPS to intersect with the existing Caliente - Coyote 115-kV transmission line. (PUCT Docket No. 41359)
	•	MPS to Montwood: a 115-kV transmission line from the MPS to the existing Montwood Substation in east El Paso. (PUCT Docket No. 41809)
	The transmission CCN filings for both the MPS to Caliente and the MPS In & Out were filed on April 15, 2013, and the transmission CCN filing for the MPS to Montwood was filed on September 24, 2013. The Company is requesting to build these transmission lines to connect the new MPS to the electrical grid in order to meet expected customer growth and electric demand and to improve system reliability. A final order approving a unanimous settlement in the MPS to Caliente transmission CCN filing was received on March 10, 2014. Hearings on the MPS to Montwood and MPS In & Out transmission line CCN cases have been suspended as the parties in the cases seek to negotiate settlements. The Company is unable to predict the outcome of these settlement negotiations. A final order is expected in the fall of 2014.
	Other Required Approvals. The Company has obtained other required approvals for recovery of fuel costs through fixed fuel factors, other tariffs and approvals as required by the Public Utility Regulatory Act (the "PURA") and the PUCT.
	New Mexico Regulatory Matters
	2009 New Mexico Stipulation. On December 10, 2009, the NMPRC issued a final order conditionally approving the stipulated rates in NMPRC Case No. 09-00171-UT. The stipulated rates went into effect with January 2010 bills. The stipulated rates provide for an Efficient Use of Energy Factor Rate Rider to recover energy efficiency expenditures which requires an annual filing and approval of the related incentives and adjustments to the recovery factors.
	Fuel and purchased power costs in New Mexico are recovered through a Fuel and Purchased Power Cost Adjustment Clause (the "FPPCAC"). On January 8, 2014, the NMPRC approved the continuation of the FPPCAC without modification in NMPRC Case No. 13-00380-UT. The Company recovers its investment in Palo Verde Unit 3 in New Mexico through the FPPCAC as purchased power using a proxy market price approved in the 2009 New Mexico rate stipulation.
	Montana Power Station Approvals. The Company has received a CCN authorization from the NMPRC to construct the first two (of four) units of the MPS. As discussed above, the Company also had to obtain air permits from the TCEQ and EPA before it could begin construction. On September 6, 2013, the Company filed an application with the NMPRC for issuance of a CCN to construct, own and operate two additional 88 MW natural gas-fired generating units designated as the MPS Units 3 and 4 in El Paso County, Texas. The case has been designated NMPRC Case No. 13-00297-UT. No protests to the Company's application were filed and the hearing examiner issued a recommended decision to approve the Company's application on February 20, 2014. A final order is expected in the second quarter of 2014.
	Revolving Credit Facility, Issuance of Long-Term Debt and Guarantee of Debt. On October 30, 2013, the Company received approval in NMPRC Case No. 13-00317-UT to amend its current $300 million Revolving Credit Facility ("RCF") to include an option, subject to lender's approval, to expand the amount of the potential borrowings available under the facility to $400 million and extend the maturity date by up to four years; issue up to $300 million in new long-term debt; and to guarantee the issuance of up to $50 million of new debt by Rio Grande Resources Trust ("RGRT") to finance future purchases of nuclear fuel and to refinance existing debt obligations related to the financing of purchases of nuclear fuel.
	On January 14, 2014, the Company and RGRT entered into a second amended and restated credit agreement related to the RCF with JP Morgan Chase Bank, N.A., as administrative agent and issuing bank, and Union Bank, N.A., as syndication agent, and various lending banks party thereto. Under the terms of the agreement, the Company has available $300 million and the ability to increase the RCF by up to $100 million (up to a total of $400 million) upon the satisfaction of certain conditions, more fully set forth in the agreement, including obtaining commitments from lenders or third party financial institutions. The RCF has a term ending January 2019. The Company may extend the maturity date up to two times, in each case for an additional one year period upon the satisfaction of certain conditions.
	Other Required Approvals. The Company has obtained other required approvals for other tariffs, securities transactions, long-term resource plans, recovery of energy efficiency costs through a base rate rider and other approvals as required by the NMPRC.
	Federal Regulatory Matters
	Public Service Company of New Mexico's ("PNM") 2010 Transmission Rate Case. On October 27, 2010, PNM filed a Notice of Transmission Rate Change for transmission delivery services provided by PNM. These rates went into effect on June 1, 2011. The Company takes transmission service from PNM. On January 2, 2013, the FERC issued a letter order approving a unanimous stipulation and agreement. Pursuant to the stipulation, on January 31, 2013, PNM refunded $1.9 million, for amounts that PNM collected since June 1, 2011, in excess of settlement rates. This amount was recorded in the fourth quarter of 2012 as a reduction of transmission expense.
	Revolving Credit Facility, Issuance of Long-Term Debt and Guarantee of Debt. On November 15, 2013, the FERC issued an order in Docket No. ES13-59-000 approving the Company's filing to amend its current $300 million RCF to include an option, subject to lender's approval, to expand the amount of the potential borrowings available under the facility to $400 million and extend the maturity date by up to four years; issue up to $300 million in new long-term debt; and to guarantee the issuance of up to $50 million of new debt by RGRT to finance future purchases of nuclear fuel and to refinance existing debt obligations related to the purchase of nuclear fuel. As noted above, on January 14, 2014, the Company and RGRT entered into a second amended and restated credit agreement related to the RCF.
	Other Required Approvals. The Company has obtained required approvals for rates and tariffs, securities transactions and other approvals as required by the FERC.

Common_Stock

Common Stock	3 Months Ended
	Mar. 31, 2014
Class of Stock Disclosures [Abstract]	'
Shareholders' Equity and Share-based Payments, Including Earnings Per Share Information	'
	Common Stock
	Dividend Policy. The Company paid $10.7 million and $10.1 million in quarterly cash dividends during the three months ended March 31, 2014 and 2013, respectively. The Company paid a total of $42.7 million and $40.1 million in quarterly cash dividends during the twelve months ended March 31, 2014 and 2013, respectively.
	Basic and Diluted Earnings Per Share. The basic and diluted earnings per share are presented below (in thousands except for share data):
		Three Months Ended March 31,							Twelve Months Ended March 31,
		2014				2013			2014			2013
	Weighted average number of common shares outstanding:
	Basic number of common shares outstanding	40,149,083				40,078,061			40,132,106			40,015,380
	Dilutive effect of unvested performance awards	—				—			12,053			50,206
	Dilutive effect of stock options	—				—			—			9,234
	Diluted number of common shares outstanding	40,149,083				40,078,061			40,144,159			40,074,820
	Basic net income per common share:
	Net income	$	4,615			$	7,634		$	85,564		$	95,136
	Income allocated to participating restricted stock	(36		)		(26		)	(260		)	(248		)
	Net income available to common shareholders	$	4,579			$	7,608		$	85,304		$	94,888
	Diluted net income per common share:
	Net income	$	4,615			$	7,634		$	85,564		$	95,136
	Income reallocated to participating restricted stock	(36		)		(26		)	(260		)	(247		)
	Net income available to common shareholders	$	4,579			$	7,608		$	85,304		$	94,889
	Basic net income per common share:
	Distributed earnings	$	0.265			$	0.25		$	1.06		$	1
	Undistributed earnings	(0.155		)		(0.06		)	1.07			1.37
	Basic net income per common share	$	0.11			$	0.19		$	2.13		$	2.37
	Diluted net income per common share:
	Distributed earnings	$	0.265			$	0.25		$	1.06		$	1
	Undistributed earnings	(0.155		)		(0.06		)	1.06			1.37
	Diluted net income per common share	$	0.11			$	0.19		$	2.12		$	2.37
	The amount of restricted stock awards and performance shares at 100% performance level excluded from the calculation of the diluted number of common shares outstanding because their effect was antidilutive is presented below:
		Three Months Ended						Twelve Months Ended
		March 31,						March 31,
		2014			2013			2014		2013
	Restricted stock awards	79,413			56,101			57,017		44,253
	Performance shares (a)	128,508			124,997			90,384		78,112
	____________________
	(a)	Certain performance shares were excluded from the computation of diluted earnings per share as no payouts would have been required based upon performance at the end of each corresponding period.

Income_Taxes

Income Taxes	3 Months Ended
	Mar. 31, 2014
Components of Income Tax Expense (Benefit), Continuing Operations [Abstract]	'
Income Taxes	'
	Income Taxes
	The Company files income tax returns in the United States ("U.S.") federal jurisdiction and in the states of Texas, New Mexico and Arizona. The Company is no longer subject to tax examination by the taxing authorities in the federal and New Mexico jurisdictions for years prior to 2009 and in Arizona for years prior to 2008. The Company is currently under audit in Texas for tax years 2007 through 2011. The Company reached a settlement with the Arizona Department of Revenue in March 2014 in their audit of income tax returns for the years 1998 through 2007 which did not have a material effect on income tax expense.
	For the three months ended March 31, 2014 and 2013, the Company’s effective tax rate was 24.2% and 30.3%, respectively. For the twelve months ended March 31, 2014 and 2013, the Company's effective tax rate was 32.8% and 34.2%, respectively. The Company's effective tax rate for the three months ended March 31, 2014 differs from the federal statutory tax rate of 35.0% primarily due to capital gains in the decommissioning trusts realized in the first quarter of 2014, which are taxed at a federal rate of 20.0%, the allowance for equity funds used during construction and state income taxes. The Company's effective tax rate for the three months ended March 31, 2013 and the twelve months ended March 31, 2014 and 2013 differs from the federal statutory tax rate of 35.0% primarily due to the allowance for equity funds used during construction and state income taxes.

Commitments_Contingencies_And_

Commitments, Contingencies And Uncertainties	3 Months Ended
	Mar. 31, 2014
Commitments and Contingencies Disclosure [Abstract]	'
Commitments, Contingencies And Uncertainties	'
	Commitments, Contingencies and Uncertainties
	For a full discussion of commitments and contingencies, see Note K of Notes to Financial Statements in the 2013 Form 10-K. In addition, see Note C above and Notes C and E of Notes to Financial Statements in the 2013 Form 10-K regarding matters related to wholesale power sales contracts and transmission contracts subject to regulation and Palo Verde, including decommissioning, spent nuclear fuel and waste disposal, and liability and insurance matters.
	Power Purchase and Sale Contracts
	To supplement its own generation and operating reserves, and to meet required renewable portfolio standards, the Company engages in firm power purchase arrangements which may vary in duration and amount based on evaluation of the Company’s resource needs, the economics of the transactions, and specific renewable portfolio requirements. For a full discussion of power purchase and sale contracts that the Company has entered into with various counterparties, see Note K of Notes to Financial Statements in the 2013 Form 10-K. In addition the 50 MW Macho Springs solar photovoltaic project located in Luna County, New Mexico, is projected to begin commercial operation before June 2014.
	Environmental Matters
	General. The Company is subject to extensive laws, regulations and permit requirements with respect to air and greenhouse gas emissions, water discharges, soil and water quality, waste management and disposal, natural resources and other environmental matters by federal, state, regional, tribal and local authorities. Failure to comply with such laws, regulations and requirements can result in actions by authorities or other third parties that might seek to impose on the Company administrative, civil and/or criminal penalties or other sanctions. In addition, releases of pollutants or contaminants into the environment can result in costly cleanup liabilities. These laws, regulations and requirements are subject to change through modification or reinterpretation, or the introduction of new laws and regulations and, as a result, the Company may face additional capital and operating costs to comply. For a full discussion of certain key environmental issues, laws and regulations facing the Company see Note K of Notes to Financial Statements in the 2013 Form 10-K.
	Clean Air Interstate Rule/Cross State Air Pollution Rule. The EPA promulgated the Cross-State Air Pollution Rule ("CSAPR") in August 2011, which rule involves requirements to limit emissions of nitrogen oxides ("NOx") and sulfur dioxide ("SO2") from certain of the Company's power plants in Texas and/or purchase allowances representing other parties' emissions reductions. CSAPR was intended to replace the EPA's 2005 Clean Air Interstate Rule ("CAIR"). While the U.S. Court of Appeals for the District of Columbia Circuit ("D.C. Court of Appeals") vacated CSAPR in August 2012 and allowed CAIR to stand until the EPA issued a proper replacement, on April 29, 2014, the U.S. Supreme Court upheld CSAPR, remanding certain portions of CSAPR to the D.C. Court of Appeals for consideration. The Company will evaluate what impact, if any, the D.C. Court of Appeals subsequent holdings on remand will have on its operations.
	Other Laws and Regulations and Risks. The Company intends to cease its participation in Four Corners Generating Station ("Four Corners") at the expiration of the 50-year participation agreement in 2016. The Company believes that it has better economic and cleaner alternatives for serving the energy needs of its customers than coal-fired generation, which is subject to extensive regulation and litigation. For example, as a result of Arizona Public Service Company's ("APS") recent Best Available Retrofit Technology Federal Implementation Plan compliance strategy notification to the EPA, Four Corners is required to install expensive pollution control equipment in order to continue operation in the future. The Company's share of the cost of these controls is currently estimated by APS to be approximately $39 million if the Company were to extend its participation in the plant. In addition, the EPA has entered into a consent decree which would require it to issue its final rulemaking regarding the regulation of coal combustion residuals ("CCR") under the federal Resource, Conservation and Recovery Act by December 19, 2014. Once issued, the Company may be required to incur significant costs to address CCRs either generated in the past and disposed of at or from Four Corners, as well as CCRs generated in connection with the ongoing operations of Four Corners. Further, assured supplies of water are important for the Company's operations and assets, including Four Corners. Four Corners is located in a region that has been experiencing drought conditions which could affect the plant's water supply. Four Corners has accordingly been involved in negotiations and proceedings with third parties relating to water supply issues. The drought conditions and related negotiations and proceedings could adversely affect the amount of power available, or the price thereof, from Four Corners. The Company is negotiating with APS on the disposition of its ownership interest of Four Corners to allow the other participants to pursue a life extension of the Four Corners plant.
	Climate Change. On June 25, 2013, President Obama set forth his plan to address climate change. He reiterated a goal of reducing greenhouse gas emissions ("GHG") "in the range of 17 percent" below 2005 levels by 2020. The plan included a variety of executive actions, including future regulatory measures to reduce carbon emissions from power plants. In a White House memorandum of the same date, the President directed the EPA to issue a new proposal for GHG rulemaking addressing new power plants by September 20, 2013, and a rule for existing power plants by June 1, 2014. The formal proposal for new power plants was published in the Federal Register on January 8, 2014. The Company continues its review of the new proposal and plans to participate in the post-publication comment period (with extension) ending May 9, 2014. Given the very significant remaining uncertainties regarding these rules, the Company believes it is impossible to meaningfully quantify the costs of these potential requirements at present.
	Environmental Litigation and Investigations. Since 2009, the EPA and certain environmental organizations have been scrutinizing, and in some cases, have filed lawsuits, relating to certain air emissions and air permitting matters related to Four Corners. In particular, since July 2011, the U.S. Department of Justice (the "DOJ"), on behalf of the EPA, and APS have been engaged in substantive settlement negotiations in an effort to resolve the pending matters. The allegations being addressed through settlement negotiations are that APS failed to obtain the necessary permits and install the controls necessary under the U.S. Clean Air Act ("CAA") to reduce SO2, NOx, and particular matter ("PM"), and that defendants failed to obtain an operating permit under Title V of the CAA that reflects applicable requirements imposed by law. In March 2012, the DOJ provided APS with a draft consent decree to settle the EPA matter, which decree contains specific provisions for the reduction and control of NOx, SO2, and PM, as well as provisions for a civil penalty, and expenditures on environmental mitigation projects with an emphasis on projects that address alleged harm to the Navajo Nation. Settlement discussions are on-going and the Company is unable to predict the outcome of these settlement negotiations. The Company has accrued a total of $0.5 million as a loss contingency related to this matter.
	The Company received notice that Earthjustice filed a lawsuit in the United States District Court for New Mexico on October 4, 2011 for alleged violations of the Prevention of Significant Deterioration ("PSD") provisions of the CAA related to Four Corners. On January 6, 2012, Earthjustice filed a First Amended Complaint adding claims for violations of the CAA's New Source Performance Standards ("NSPS") program. Among other things, the plaintiffs seek to have the court enjoin operations at Four Corners until APS applies for and obtains any required PSD permits and complies with the referenced NSPS program. The plaintiffs further request the court to order the payment of civil penalties, including a beneficial mitigation project. On April 2, 2012, APS and the other Four Corners' participants filed motions to dismiss with the court. The case is being held in abeyance while the parties seek to negotiate a settlement. On March 30, 2013, upon joint motion of the parties, the court issued an order deeming the motions to dismiss withdrawn without prejudice during pendency of the stay. At such time as the stay is lifted, APS, the Company and the other Four Corners participants may reinstate the motions to dismiss. On April 25, 2014, the stay was extended until May 15, 2014. The Company is unable to predict the outcome of this litigation.
	New Mexico Tax Matter Related to Coal Supplied to Four Corners
	On May 23, 2013, the New Mexico Taxation and Revenue Department issued a notice of assessment for coal severance surtax, penalty, and interest totaling approximately $30 million related to coal supplied under the coal supply agreement for Four Corners (the "Assessment"). The Company's share of the Assessment is approximately $1.5 million. On behalf of the Four Corners participants, the coal supplier made a partial payment of the Assessment and immediately filed a refund claim with respect to that partial payment in August 2013. The New Mexico Taxation and Revenue Department denied the refund claim. On December 19, 2013, the coal supplier and APS, on its own behalf and as operating agent for Four Corners, filed complaints with the New Mexico District Court contesting both the validity of the Assessment and the refund claim denial. APS believes the Assessment and the refund claim denial are without merit. The Company cannot predict the timing, results, or potential impacts of the outcome of this litigation.

Litigation

Litigation	3 Months Ended
	Mar. 31, 2014
Litigation [Abstract]	'
Litigation Matters Disclosure	'
	Litigation
	The Company is a party to various legal actions. In many of these matters, the Company has excess casualty liability insurance that covers the various claims, actions and complaints. Based on a review of these claims and applicable insurance coverage, the Company believes that none of these claims will have a material adverse effect on the financial position, results of operations or cash flows of the Company. See Note C above and Note C of the Notes to Financial Statements in the 2013 Form 10-K for discussion of the effects of government legislation and regulation on the Company.

Employee_Benefits

Employee Benefits	3 Months Ended
	Mar. 31, 2014
General Discussion of Pension and Other Postretirement Benefits [Abstract]	'
Employee Benefits	'
	Employee Benefits
	Retirement Plans
	The net periodic benefit cost recognized for the three and twelve months ended March 31, 2014 and 2013 is made up of the components listed below as determined using the projected unit credit actuarial cost method (in thousands):
		Three Months Ended						Twelve Months Ended
		March 31,						March 31,
		2014			2013			2014			2013
	Components of net periodic benefit cost:
	Service cost	$	2,173		$	2,400		$	9,100		$	9,004
	Interest cost	3,870			3,400			14,084			13,579
	Expected return on plan assets	(4,680		)	(4,275		)	(17,513		)	(15,108		)
	Amortization of:
	Net loss	1,773			2,675			10,196			11,066
	Prior service (benefit) cost	(259		)	25			(187		)	113
	Net periodic benefit cost	$	2,877		$	4,225		$	15,680		$	18,654
	During the three months ended March 31, 2014, the Company contributed $3.5 million of its projected $8.7 million 2014 annual contribution to its retirement plans.
	During the quarter ended March 31, 2014, the Company implemented certain amendments to the Retirement Income Plan and Excess Benefit Plan. In the first quarter of 2014, the Company offered a cash balance pension plan as an alternative to its current final average pay pension plan for employees hired prior to January 1, 2014. The cash balance pension plan also included an enhanced employer matching contribution to the employee's respective 401(k) Defined Contribution Plan. The revisions in the benefit plans were effective April 1, 2014. As a result of these actions, the Company remeasured the assets and liabilities of the retirement plans based on actuarially determined estimates, using the end of alternative choice date of February 28, 2014 as the remeasurement date. The discount rate used to remeasure the benefit obligation at February 28, 2014 was 4.6% for the Retirement Income Plan and 4.5% for the Excess Benefit Plan, compared to 4.9% for both plans at December 31, 2013. As a result of the changes described above, the benefit obligation of the affected plans decreased $19.7 million, accumulated other comprehensive income before income taxes increased $19.7 million, estimated future benefit payments from 2014 through 2018 increased $17.2 million compared to the previous estimates. The 2014 net periodic benefit cost is estimated to decrease by $8.4 million compared to the net periodic benefit cost incurred in 2013 due to the changes described above and revisions to actuarial assumptions.
	Other Postretirement Benefits
	The net periodic benefit cost recognized for the three and twelve months ended March 31, 2014 and 2013 is made up of the components listed below (in thousands):
		Three Months Ended						Twelve Months Ended
		March 31,						March 31,
		2014			2013			2014			2013
	Components of net periodic benefit cost:
	Service cost	$	700		$	1,100		$	3,443		$	4,408
	Interest cost	1,125			1,375			4,906			5,611
	Expected return on plan assets	(525		)	(475		)	(2,001		)	(1,754		)
	Amortization of:
	Prior service benefit	(1,200		)	(1,425		)	(5,432		)	(5,832		)
	Net (gain) loss	(650		)	—			(1,276		)	455
	Net periodic benefit cost (benefit)	$	(550	)	$	575		$	(360	)	$	2,888
	The Company has not contributed to its other postretirement benefits plan during the three months ended March 31, 2014 and does not expect to contribute to its other postretirement benefit plan in 2014.

Financial_Instruments_And_Inve

Financial Instruments And Investments (Notes)	3 Months Ended
	Mar. 31, 2014
Financial Instruments And Investments [Abstract]	'
Financial Instruments and Investments	'
	Financial Instruments and Investments
	FASB guidance requires the Company to disclose estimated fair values for its financial instruments. The Company has determined that cash and temporary investments, investment in debt securities, accounts receivable, decommissioning trust funds, long-term debt, short-term borrowings under the RCF, accounts payable and customer deposits meet the definition of financial instruments. The carrying amounts of cash and temporary investments, accounts receivable, accounts payable and customer deposits approximate fair value because of the short maturity of these items. Investments in debt securities and decommissioning trust funds are carried at fair value.
	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, 2014						December 31, 2013
		Carrying			Estimated			Carrying			Estimated
		Amount			Fair			Amount			Fair
					Value						Value
	Pollution Control Bonds	$	193,135		$	202,897		$	193,135		$	193,990
	Senior Notes	696,508			744,856			696,485			734,515
	RGRT Senior Notes (1)	110,000			116,560			110,000			115,850
	RCF (1)	45,951			45,951			14,352			14,352
	Total	$	1,045,594		$	1,110,264		$	1,013,972		$	1,058,707
	_______________
	-1	Nuclear fuel financing as of March 31, 2014 and December 31, 2013 is funded through the $110 million RGRT Senior Notes and $20.0 million and $14.4 million, respectively under the RCF. As of March 31, 2014, $26.0 million was outstanding under the RCF for working capital or general corporate purposes. As of December 31, 2013, no amount 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.
	Marketable Securities. The Company’s marketable securities, included in decommissioning trust funds in the balance sheets, are reported at fair value which was $217.5 million and $214.1 million at March 31, 2014 and December 31, 2013, respectively. These securities are classified as available for sale under FASB guidance for certain investments in debt and equity securities and are valued using prices and other relevant information generated by market transactions involving identical or comparable securities. The reported fair values include gross unrealized losses on marketable securities whose impairment the Company has deemed to be temporary. 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, 2014
		Less than 12 Months						12 Months or Longer						Total
		Fair			Unrealized			Fair			Unrealized			Fair		Unrealized
		Value			Losses			Value			Losses			Value		Losses
	Description of Securities (1):
	Federal Agency Mortgage Backed Securities	$	4,667		$	(28	)	$	2,457		$	(170	)	$	7,124	$	(198	)
	U.S. Government Bonds	1,548			(1		)	16,128			(893		)	17,676		(894		)
	Municipal Obligations	6,860			(101		)	13,038			(651		)	19,898		(752		)
	Corporate Obligations	2,734			(66		)	1,299			(44		)	4,033		(110		)
	Total Debt Securities	15,809			(196		)	32,922			(1,758		)	48,731		(1,954		)
	Common Stock	1,614			(122		)	—			—			1,614		(122		)
	Total Temporarily Impaired Securities	$	17,423		$	(318	)	$	32,922		$	(1,758	)	$	50,345	$	(2,076	)
	_________________
	-1	Includes approximately 119 securities.
		December 31, 2013
		Less than 12 Months						12 Months or Longer						Total
		Fair			Unrealized			Fair			Unrealized			Fair		Unrealized
		Value			Losses			Value			Losses			Value		Losses
	Description of Securities (2):
	Federal Agency Mortgage Backed Securities	$	6,444		$	(169	)	$	1,421		$	(119	)	$	7,865	$	(288	)
	U.S. Government Bonds	8,114			(245		)	10,866			(840		)	18,980		(1,085		)
	Municipal Obligations	12,286			(335		)	7,782			(479		)	20,068		(814		)
	Corporate Obligations	3,284			(96		)	901			(54		)	4,185		(150		)
	Total Debt Securities	30,128			(845		)	20,970			(1,492		)	51,098		(2,337		)
	Common Stock	2,305			(126		)	—			—			2,305		(126		)
	Total Temporarily Impaired Securities	$	32,433		$	(971	)	$	20,970		$	(1,492	)	$	53,403	$	(2,463	)
	_________________
	-2	Includes approximately 122 securities.
	The Company monitors the length of time the security trades below its cost basis along with the amount and percentage of the unrealized loss in determining if a decline in fair value of marketable securities below recorded cost is considered to be other than temporary. In addition, the Company will research the future prospects of individual securities as necessary. As a result of these factors, as well as the Company’s intent and ability to hold these securities until their market price recovers, these securities are considered temporarily impaired. The Company does not anticipate expending monies held in trust before 2044 or a later period when the Company begins to decommission Palo Verde.
	The reported fair values also include gross unrealized gains on marketable securities which have not been recognized in the Company’s net income. The table below presents the unrecognized gross unrealized gains and the fair value of these securities, aggregated by investment category (in thousands):
		March 31, 2014						December 31, 2013
		Fair			Unrealized			Fair			Unrealized
		Value			Gains			Value			Gains
	Description of Securities:
	Federal Agency Mortgage Backed Securities	$	10,276		$	489		$	9,929		$	433
	U.S. Government Bonds	9,719			180			6,258			126
	Municipal Obligations	10,237			528			8,783			450
	Corporate Obligations	9,758			649			9,188			506
	Total Debt Securities	39,990			1,846			34,158			1,515
	Common Stock	105,835			43,402			103,808			43,145
	Common Collective Trust-Equity Funds	16,891			235			—			—
	Equity Mutual Funds	—			—			16,802			3,081
	Cash and Cash Equivalents	4,448			—			5,924			—
	Total	$	167,164		$	45,483		$	160,692		$	47,741
	The Company’s marketable securities include investments in municipal, corporate and federal debt obligations. Substantially all of the Company’s mortgage-backed securities, based on contractual maturity, are due in ten years or more. The mortgage-backed securities have an estimated weighted average maturity which generally range from three years to eight years and reflects anticipated future prepayments. The contractual year for maturity of these available-for-sale securities as of March 31, 2014 is as follows (in thousands):
		Total			2014			2015			2019 through 2023			2024 and Beyond
								through
								2018
Municipal Debt Obligations	$	30,135		$	976		$	13,279		$	12,562		$	3,318
Corporate Debt Obligations	13,791			317			3,324			5,963			4,187
U.S. Government Bonds	27,395			1,210			14,347			6,434			5,404
The Company recognizes impairment losses on certain of its securities deemed to be other than temporary. In accordance with FASB guidance, these impairment losses are recognized in net income, and a lower cost basis is established for these securities. For the three and twelve months ended March 31, 2014 and 2013, 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,
	2014			2013			2014			2013
Unrealized holding losses included in pre-tax income	$	—		$	—		$	—		$	(479	)
The Company’s marketable securities in its decommissioning trust funds are sold from time to time and the Company uses the specific identification basis to determine the amount to reclassify out of accumulated other comprehensive income and into net income. The proceeds from the sale of these securities and the related effects on pre-tax income are as follows (in thousands):
	Three Months Ended						Twelve Months Ended
	March 31,						March 31,
	2014			2013			2014			2013
Proceeds from sales or maturities of available-for-sale securities	$	28,827		$	10,907		$	74,067		$	89,870
Gross realized gains included in pre-tax income	$	3,014		$	39		$	3,961		$	1,128
Gross realized losses included in pre-tax income	(149		)	(197		)	(385		)	(2,062		)
Gross unrealized losses included in pre-tax income	—			—			—			(479		)
Net gains (losses) in pre-tax income	$	2,865		$	(158	)	$	3,576		$	(1,413	)
Net unrealized holding gains included in accumulated other comprehensive income	$	998		$	6,793		$	11,904		$	8,562
Net (gains) losses reclassified out of accumulated other comprehensive income	(2,865		)	158			(3,576		)	1,413
Net gains (losses) in other comprehensive income	$	(1,867	)	$	6,951		$	8,328		$	9,975
Fair Value Measurements. FASB guidance requires the Company to provide expanded quantitative disclosures for financial assets and liabilities recorded on the balance sheet at fair value. Financial assets carried at fair value include the Company’s decommissioning trust investments and investment in debt securities which are included in deferred charges and other assets on the balance sheets. The Company has no liabilities that are measured at fair value on a recurring basis. The FASB guidance establishes a fair value hierarchy that prioritizes the inputs to valuation techniques used to measure fair value into three levels as follows:
•	Level 1 – Observable inputs that reflect quoted market prices for identical assets and liabilities in active markets. Financial assets utilizing Level 1 inputs include the nuclear decommissioning trust investments in active exchange-traded equity securities, mutual funds and U.S. Treasury securities that are in a highly liquid and active market.
•	Level 2 – Inputs other than quoted market prices included in Level 1 that are observable for the asset or liability either directly or indirectly. Financial assets utilizing Level 2 inputs include the nuclear decommissioning trust investments in fixed income securities. The fair value of these financial instruments is based on evaluated prices that reflect observable market information, such as actual trade information of similar securities, adjusted for observable differences. The Common Collective Trusts are valued using the net asset value ("NAV") provided by the administrator of the fund. The NAV price is quoted on a restrictive market although the underlying investments are traded on active markets.
•	Level 3 – Unobservable inputs using data that is not corroborated by market data and primarily based on internal Company analysis using models and various other analyses. Financial assets utilizing Level 3 inputs include the Company’s investment in debt securities.
The securities in the Company’s decommissioning trust funds are valued using prices and other relevant information generated by market transactions involving identical or comparable securities. FASB guidance identifies this valuation technique as the “market approach” with observable inputs. The Company analyzes available-for-sale securities to determine if losses are other than temporary.
During the first quarter of 2014, the Company sold its nuclear decommissioning trust investments in equity mutual funds, classified as Level 1, and invested those assets in common collective trusts which are classified as Level 2. The fair value of the Company’s decommissioning trust funds and investment in debt securities, at March 31, 2014 and December 31, 2013, and the level within the three levels of the fair value hierarchy defined by FASB guidance are presented in the table below (in thousands):
Description of Securities	Fair Value as of March 31, 2014			Quoted Prices			Significant			Significant
				in Active			Other			Unobservable
				Markets for			Observable			Inputs
				Identical Assets			Inputs			(Level 3)
				(Level 1)			(Level 2)
Trading Securities:
Investments in Debt Securities	$	1,503		$	—		$	—		$	1,503
Available for sale:
U.S. Government Bonds	$	27,395		$	27,395		$	—		$	—
Federal Agency Mortgage Backed Securities	17,400			—			17,400			—
Municipal Obligations	30,135			—			30,135			—
Corporate Obligations	13,791			—			13,791			—
Subtotal, Debt Securities	88,721			27,395			61,326			—
Common Stock	107,449			107,449			—			—
Common Collective Trust-Equity Funds	16,891			—			16,891			—
Cash and Cash Equivalents	4,448			4,448			—			—
Total available for sale	$	217,509		$	139,292		$	78,217		$	—
Description of Securities	Fair Value as of December 31, 2013			Quoted Prices			Significant			Significant
				in Active			Other			Unobservable
				Markets for			Observable			Inputs
				Identical Assets			Inputs			(Level 3)
				(Level 1)			(Level 2)
Trading Securities:
Investments in Debt Securities	$	1,555		$	—		$	—		$	1,555
Available for sale:
U.S. Government Bonds	$	25,238		$	25,238		$	—		$	—
Federal Agency Mortgage Backed Securities	17,794			—			17,794			—
Municipal Obligations	28,851			—			28,851			—
Corporate Obligations	13,373			—			13,373			—
Subtotal, Debt Securities	85,256			25,238			60,018			—
Common Stock	106,113			106,113			—			—
Equity Mutual Funds	16,802			16,802			—			—
Cash and Cash Equivalents	5,924			5,924			—			—
Total available for sale	$	214,095		$	154,077		$	60,018		$	—
There were no transfers in or out of Level 1 and Level 2 fair value measurements categories due to changes in observable inputs during the three and twelve month periods ending March 31, 2014 and 2013. There were no purchases, sales, issuances, and settlements related to the assets in the Level 3 fair value measurement category during the three and twelve months ended March 31, 2014 and 2013.

Principles_Of_Preparation_Poli

Principles Of Preparation (Policy)	3 Months Ended
	Mar. 31, 2014
Accounting Policies [Abstract]	'
Use of Estimates, Policy	'
	Use of Estimates. The preparation of financial statements in conformity with generally accepted accounting principles requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of the financial statements and the reported amounts of revenues and expenses during the reporting period. Actual results could differ from those estimates.
Revenue Recognition, Policy	'
	Revenues. Revenues related to the sale of electricity are generally recorded when service is rendered or electricity is delivered to customers. The billing of electricity sales to retail customers is based on the reading of their meters, which occurs on a systematic basis throughout the month. Unbilled revenues are estimated based on monthly generation volumes and by applying an average revenue/kWh to the number of estimated kWhs delivered but not billed. Accounts receivable included accrued unbilled revenues of $17.7 million at March 31, 2014 and $19.8 million at December 31, 2013. The Company presents revenues net of sales taxes in its statements of operations.

Principles_Of_Preparation_Prin

Principles Of Preparation Principles Of Preparation (Tables)	3 Months Ended
	Mar. 31, 2014
Supplemental Cash Flow Information [Abstract]	'
Cash Flow, Supplemental Disclosures	'
	The Company presents revenues net of sales taxes in its statements of operations.
	Supplemental Cash Flow Disclosures (in thousands)
			Three Months Ended
			March 31,
			2014			2013
	Cash paid (received) for:
		Interest on long-term debt and borrowing under the revolving credit facility	$	10,174		$	9,893
		Income tax refund, net	(767		)	(3,088		)
	Non-cash financing activities:
		Grants of restricted shares of common stock	1,197			929
		Issuance of performance shares	—			849

Accumulated_Other_Comprehensiv1

Accumulated Other Comprehensive Income (Tables)	3 Months Ended
	Mar. 31, 2014
Accumulated Other Comprehensive Income (Loss) [Line Items]	'
Schedule of Accumulated Other Comprehensive Income (Loss) [Table Text Block]	'
	Changes in Accumulated Other Comprehensive Income (Loss) (net of tax) by component which are presented below (in thousands):
			Three Months Ended March 31, 2014																Three Months Ended March 31, 2013
			Unrecognized Pension and Postretirement Benefit Costs				Net Unrealized Gains (Losses) on Marketable Securities				Net Losses on Cash Flow Hedges				Accumulated Other Comprehensive Income (Loss)				Unrecognized Pension and Postretirement Benefit Costs			Net Unrealized Gains (Losses) on Marketable Securities		Net Losses on Cash Flow Hedges			Accumulated Other Comprehensive Income (Loss)
	Balance at beginning of period		$	(21,330	)		$	36,240			$	(12,298	)		$	2,612			$	(75,737	)	$	22,194	$	(12,541	)	$	(66,084	)
		Other comprehensive income before reclassifications	12,147				799				—				12,946				—			5,543		—			5,543
		Amounts reclassified from accumulated other comprehensive income (loss)	(205		)		(2,309		)		15				(2,499		)		705			121		49			875
	Balance at end of period		$	(9,388	)		$	34,730			$	(12,283	)		$	13,059			$	(75,032	)	$	27,858	$	(12,492	)	$	(59,666	)
			Twelve Months Ended March 31, 2014																Twelve Months Ended March 31, 2013
			Unrecognized Pension and Postretirement Benefit Costs				Net Unrealized Gains (Losses) on Marketable Securities				Net Losses on Cash Flow Hedges				Accumulated Other Comprehensive Income (Loss)				Unrecognized Pension and Postretirement Benefit Costs			Net Unrealized Gains (Losses) on Marketable Securities		Net Losses on Cash Flow Hedges			Accumulated Other Comprehensive Income (Loss)
	Balance at beginning of period		$	(75,032	)		$	27,858			$	(12,492	)		$	(59,666	)		$	(77,246	)	$	20,049	$	(12,746	)	$	(69,943	)
		Other comprehensive income (loss) before reclassifications	63,599				9,738				—				73,337				(1,264		)	6,695		—			5,431
		Amounts reclassified from accumulated other comprehensive income (loss)	2,045				(2,866		)		209				(612		)		3,478			1,114		254			4,846
	Balance at end of period		$	(9,388	)		$	34,730			$	(12,283	)		$	13,059			$	(75,032	)	$	27,858	$	(12,492	)	$	(59,666	)
Reclassification out of Accumulated Other Comprehensive Income [Table Text Block]	'
	Amounts reclassified from accumulated other comprehensive income (loss) for the three and twelve months ended March 31, 2014 and 2013 are as follows ( in thousands):
	Details about Accumulated Other Comprehensive Income (Loss) Components			Three Months Ended March 31,								Twelve Months Ended March 31,								Affected Line Item in the Statement of Operations
				2014				2013				2014				2013
	Amortization of pension and postretirement benefit costs:
		Prior service benefit		$	1,459			1,400				$	5,619			$	5,719			(a)
		Net loss		(1,123		)		(2,675		)		(8,920		)		(11,521		)		(a)
				336				(1,275		)		(3,301		)		(5,802		)		(a)
		Income tax effect		(131		)		570				1,256				2,324
				205				(705		)		(2,045		)		(3,478		)		(a)
	Marketable securities:
		Net realized gain (loss) on sale of securities		2,865				(158		)		3,576				(934		)		Investment and interest income, net
		Unrealized losses on available-for-sale securities included in pre-tax income		—				—				—				(479		)		Investment and interest income, net
				2,865				(158		)		3,576				(1,413		)		Income before income taxes
				(556		)		37				(710		)		299				Income tax expense
				2,309				(121		)		2,866				(1,114		)		Net income
	Loss on cash flow hedge:
		Amortization of loss		(107		)		(101		)		(417		)		(392		)		Interest on long-term debt and revolving credit facility
				(107		)		(101		)		(417		)		(392		)		Income before income taxes
				92				52				208				138				Income tax expense
				(15		)		(49		)		(209		)		(254		)		Net income
		Total reclassifications		$	2,499			$	(875	)		$	612			$	(4,846	)
	(a) These items are included in the computation of net periodic benefit cost. See Note H, Employee Benefits, for additional information.

Common_Stock_Tables

Common Stock (Tables)	3 Months Ended
	Mar. 31, 2014
Class of Stock Disclosures [Abstract]	'
Schedule of Earnings Per Share, Basic and Diluted	'
	Basic and Diluted Earnings Per Share. The basic and diluted earnings per share are presented below (in thousands except for share data):
		Three Months Ended March 31,							Twelve Months Ended March 31,
		2014				2013			2014			2013
	Weighted average number of common shares outstanding:
	Basic number of common shares outstanding	40,149,083				40,078,061			40,132,106			40,015,380
	Dilutive effect of unvested performance awards	—				—			12,053			50,206
	Dilutive effect of stock options	—				—			—			9,234
	Diluted number of common shares outstanding	40,149,083				40,078,061			40,144,159			40,074,820
	Basic net income per common share:
	Net income	$	4,615			$	7,634		$	85,564		$	95,136
	Income allocated to participating restricted stock	(36		)		(26		)	(260		)	(248		)
	Net income available to common shareholders	$	4,579			$	7,608		$	85,304		$	94,888
	Diluted net income per common share:
	Net income	$	4,615			$	7,634		$	85,564		$	95,136
	Income reallocated to participating restricted stock	(36		)		(26		)	(260		)	(247		)
	Net income available to common shareholders	$	4,579			$	7,608		$	85,304		$	94,889
	Basic net income per common share:
	Distributed earnings	$	0.265			$	0.25		$	1.06		$	1
	Undistributed earnings	(0.155		)		(0.06		)	1.07			1.37
	Basic net income per common share	$	0.11			$	0.19		$	2.13		$	2.37
	Diluted net income per common share:
	Distributed earnings	$	0.265			$	0.25		$	1.06		$	1
	Undistributed earnings	(0.155		)		(0.06		)	1.06			1.37
	Diluted net income per common share	$	0.11			$	0.19		$	2.12		$	2.37
Schedule of Antidilutive Securities Excluded From Computation Of Earnings Per Share	'
	The amount of restricted stock awards and performance shares at 100% performance level excluded from the calculation of the diluted number of common shares outstanding because their effect was antidilutive is presented below:
		Three Months Ended						Twelve Months Ended
		March 31,						March 31,
		2014			2013			2014		2013
	Restricted stock awards	79,413			56,101			57,017		44,253
	Performance shares (a)	128,508			124,997			90,384		78,112
	____________________
	(a)	Certain performance shares were excluded from the computation of diluted earnings per share as no payouts would have been required based upon performance at the end of each corresponding period.

Employee_Benefits_Tables

Employee Benefits (Tables)	3 Months Ended
	Mar. 31, 2014
Retirement Plans	'
Defined Benefit Plan Disclosure [Line Items]	'
Schedule of Net Benefit Costs	'
	The net periodic benefit cost recognized for the three and twelve months ended March 31, 2014 and 2013 is made up of the components listed below as determined using the projected unit credit actuarial cost method (in thousands):
		Three Months Ended						Twelve Months Ended
		March 31,						March 31,
		2014			2013			2014			2013
	Components of net periodic benefit cost:
	Service cost	$	2,173		$	2,400		$	9,100		$	9,004
	Interest cost	3,870			3,400			14,084			13,579
	Expected return on plan assets	(4,680		)	(4,275		)	(17,513		)	(15,108		)
	Amortization of:
	Net loss	1,773			2,675			10,196			11,066
	Prior service (benefit) cost	(259		)	25			(187		)	113
	Net periodic benefit cost	$	2,877		$	4,225		$	15,680		$	18,654
Other Postretirement Benefit Plans, Defined Benefit	'
Defined Benefit Plan Disclosure [Line Items]	'
Schedule of Net Benefit Costs	'
	The net periodic benefit cost recognized for the three and twelve months ended March 31, 2014 and 2013 is made up of the components listed below (in thousands):
		Three Months Ended						Twelve Months Ended
		March 31,						March 31,
		2014			2013			2014			2013
	Components of net periodic benefit cost:
	Service cost	$	700		$	1,100		$	3,443		$	4,408
	Interest cost	1,125			1,375			4,906			5,611
	Expected return on plan assets	(525		)	(475		)	(2,001		)	(1,754		)
	Amortization of:
	Prior service benefit	(1,200		)	(1,425		)	(5,432		)	(5,832		)
	Net (gain) loss	(650		)	—			(1,276		)	455
	Net periodic benefit cost (benefit)	$	(550	)	$	575		$	(360	)	$	2,888

Financial_Instruments_And_Inve1

Financial Instruments And Investments (Tables)	3 Months Ended
	Mar. 31, 2014
Financial Instruments And Investments [Abstract]	'
Fair Values Of Long-Term Debt And Short-Term Borrowings Under the RCF	'
	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, 2014						December 31, 2013
		Carrying			Estimated			Carrying			Estimated
		Amount			Fair			Amount			Fair
					Value						Value
	Pollution Control Bonds	$	193,135		$	202,897		$	193,135		$	193,990
	Senior Notes	696,508			744,856			696,485			734,515
	RGRT Senior Notes (1)	110,000			116,560			110,000			115,850
	RCF (1)	45,951			45,951			14,352			14,352
	Total	$	1,045,594		$	1,110,264		$	1,013,972		$	1,058,707
	_______________
	-1	Nuclear fuel financing as of March 31, 2014 and December 31, 2013 is funded through the $110 million RGRT Senior Notes and $20.0 million and $14.4 million, respectively under the RCF. As of March 31, 2014, $26.0 million was outstanding under the RCF for working capital or general corporate purposes. As of December 31, 2013, no amount 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, 2014
		Less than 12 Months						12 Months or Longer						Total
		Fair			Unrealized			Fair			Unrealized			Fair		Unrealized
		Value			Losses			Value			Losses			Value		Losses
	Description of Securities (1):
	Federal Agency Mortgage Backed Securities	$	4,667		$	(28	)	$	2,457		$	(170	)	$	7,124	$	(198	)
	U.S. Government Bonds	1,548			(1		)	16,128			(893		)	17,676		(894		)
	Municipal Obligations	6,860			(101		)	13,038			(651		)	19,898		(752		)
	Corporate Obligations	2,734			(66		)	1,299			(44		)	4,033		(110		)
	Total Debt Securities	15,809			(196		)	32,922			(1,758		)	48,731		(1,954		)
	Common Stock	1,614			(122		)	—			—			1,614		(122		)
	Total Temporarily Impaired Securities	$	17,423		$	(318	)	$	32,922		$	(1,758	)	$	50,345	$	(2,076	)
	_________________
	-1	Includes approximately 119 securities.
		December 31, 2013
		Less than 12 Months						12 Months or Longer						Total
		Fair			Unrealized			Fair			Unrealized			Fair		Unrealized
		Value			Losses			Value			Losses			Value		Losses
	Description of Securities (2):
	Federal Agency Mortgage Backed Securities	$	6,444		$	(169	)	$	1,421		$	(119	)	$	7,865	$	(288	)
	U.S. Government Bonds	8,114			(245		)	10,866			(840		)	18,980		(1,085		)
	Municipal Obligations	12,286			(335		)	7,782			(479		)	20,068		(814		)
	Corporate Obligations	3,284			(96		)	901			(54		)	4,185		(150		)
	Total Debt Securities	30,128			(845		)	20,970			(1,492		)	51,098		(2,337		)
	Common Stock	2,305			(126		)	—			—			2,305		(126		)
	Total Temporarily Impaired Securities	$	32,433		$	(971	)	$	20,970		$	(1,492	)	$	53,403	$	(2,463	)
	_________________
	-2	Includes approximately 122 securities.
	The Company monitors the length of time the security trades below its cost basis along with the amount and percentage of the unrealized loss in determining if a decline in fair value of marketable securities below recorded cost is considered to be other than temporary. In addition, the Company will research the future prospects of individual securities as necessary. As a result of these factors, as well as the Company’s intent and ability to hold these securities until their market price recovers, these securities are considered temporarily impaired. The Company does not anticipate expending monies held in trust before 2044 or a later period when the Company begins to decommission Palo Verde.
	The reported fair values also include gross unrealized gains on marketable securities which have not been recognized in the Company’s net income. The table below presents the unrecognized gross unrealized gains and the fair value of these securities, aggregated by investment category (in thousands):
		March 31, 2014						December 31, 2013
		Fair			Unrealized			Fair			Unrealized
		Value			Gains			Value			Gains
	Description of Securities:
	Federal Agency Mortgage Backed Securities	$	10,276		$	489		$	9,929		$	433
	U.S. Government Bonds	9,719			180			6,258			126
	Municipal Obligations	10,237			528			8,783			450
	Corporate Obligations	9,758			649			9,188			506
	Total Debt Securities	39,990			1,846			34,158			1,515
	Common Stock	105,835			43,402			103,808			43,145
	Common Collective Trust-Equity Funds	16,891			235			—			—
	Equity Mutual Funds	—			—			16,802			3,081
	Cash and Cash Equivalents	4,448			—			5,924			—
	Total	$	167,164		$	45,483		$	160,692		$	47,741
Contractual Year For Maturity Of Available-For-Sale Securities	'
	The contractual year for maturity of these available-for-sale securities as of March 31, 2014 is as follows (in thousands):
		Total			2014			2015			2019 through 2023			2024 and Beyond
								through
								2018
	Municipal Debt Obligations	$	30,135		$	976		$	13,279		$	12,562		$	3,318
	Corporate Debt Obligations	13,791			317			3,324			5,963			4,187
	U.S. Government Bonds	27,395			1,210			14,347			6,434			5,404
Unrealized Holding Losses Included In Pre-Tax Income	'
	For the three and twelve months ended March 31, 2014 and 2013, 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,
		2014			2013			2014			2013
	Unrealized holding losses included in pre-tax income	$	—		$	—		$	—		$	(479	)
Sale of Securities And The Related Effects On Pre-Tax Income	'
	The proceeds from the sale of these securities and the related effects on pre-tax income are as follows (in thousands):
		Three Months Ended						Twelve Months Ended
		March 31,						March 31,
		2014			2013			2014			2013
	Proceeds from sales or maturities of available-for-sale securities	$	28,827		$	10,907		$	74,067		$	89,870
	Gross realized gains included in pre-tax income	$	3,014		$	39		$	3,961		$	1,128
	Gross realized losses included in pre-tax income	(149		)	(197		)	(385		)	(2,062		)
	Gross unrealized losses included in pre-tax income	—			—			—			(479		)
	Net gains (losses) in pre-tax income	$	2,865		$	(158	)	$	3,576		$	(1,413	)
	Net unrealized holding gains included in accumulated other comprehensive income	$	998		$	6,793		$	11,904		$	8,562
	Net (gains) losses reclassified out of accumulated other comprehensive income	(2,865		)	158			(3,576		)	1,413
	Net gains (losses) in other comprehensive income	$	(1,867	)	$	6,951		$	8,328		$	9,975
Fair Value, Measurement Inputs, Disclosure	'
	The fair value of the Company’s decommissioning trust funds and investment in debt securities, at March 31, 2014 and December 31, 2013, and the level within the three levels of the fair value hierarchy defined by FASB guidance are presented in the table below (in thousands):
	Description of Securities	Fair Value as of March 31, 2014			Quoted Prices			Significant			Significant
					in Active			Other			Unobservable
					Markets for			Observable			Inputs
					Identical Assets			Inputs			(Level 3)
					(Level 1)			(Level 2)
	Trading Securities:
	Investments in Debt Securities	$	1,503		$	—		$	—		$	1,503
	Available for sale:
	U.S. Government Bonds	$	27,395		$	27,395		$	—		$	—
	Federal Agency Mortgage Backed Securities	17,400			—			17,400			—
	Municipal Obligations	30,135			—			30,135			—
	Corporate Obligations	13,791			—			13,791			—
	Subtotal, Debt Securities	88,721			27,395			61,326			—
	Common Stock	107,449			107,449			—			—
	Common Collective Trust-Equity Funds	16,891			—			16,891			—
	Cash and Cash Equivalents	4,448			4,448			—			—
	Total available for sale	$	217,509		$	139,292		$	78,217		$	—
	Description of Securities	Fair Value as of December 31, 2013			Quoted Prices			Significant			Significant
					in Active			Other			Unobservable
					Markets for			Observable			Inputs
					Identical Assets			Inputs			(Level 3)
					(Level 1)			(Level 2)
	Trading Securities:
	Investments in Debt Securities	$	1,555		$	—		$	—		$	1,555
	Available for sale:
	U.S. Government Bonds	$	25,238		$	25,238		$	—		$	—
	Federal Agency Mortgage Backed Securities	17,794			—			17,794			—
	Municipal Obligations	28,851			—			28,851			—
	Corporate Obligations	13,373			—			13,373			—
	Subtotal, Debt Securities	85,256			25,238			60,018			—
	Common Stock	106,113			106,113			—			—
	Equity Mutual Funds	16,802			16,802			—			—
	Cash and Cash Equivalents	5,924			5,924			—			—
	Total available for sale	$	214,095		$	154,077		$	60,018		$	—

Principles_Of_Preparation_Accr

Principles Of Preparation (Accrued Unbilled Revenues) (Details) (USD $)	Mar. 31, 2014	Dec. 31, 2013
In Millions, unless otherwise specified
Accounting Policies [Abstract]	'	'
Accrued unbilled revenues	$17.70	$19.80

Principles_Of_Preparation_Supp

Principles Of Preparation (Supplemental Cash Flow Disclosures) (Details) (USD $)	3 Months Ended
In Thousands, unless otherwise specified	Mar. 31, 2014	Mar. 31, 2013
Supplemental Cash Flow Information [Abstract]	'	'
Interest on long-term debt and borrowing under the revolving credit facility	$10,174	$9,893
Income tax refund, net	-767	-3,088
Grants of restricted shares of common stock	1,197	929
Issuance of performance shares	$0	$849

Accumulated_Other_Comprehensiv2

Accumulated Other Comprehensive Income by Component (Details) (USD $)	3 Months Ended		12 Months Ended
In Thousands, unless otherwise specified	Mar. 31, 2014	Mar. 31, 2013	Mar. 31, 2014	Mar. 31, 2013
Accumulated Other Comprehensive Income (Loss) [Line Items]	'	'	'	'
Accumulated Other Comprehensive Income (Loss), beginning balance	$2,612	($66,084)	($59,666)	($69,943)
Other Comprehensive Income (Loss) before Reclassifications	12,946	5,543	73,337	5,431
Amounts Reclassified from Accumulated Other Comprehensive Income (Loss)	-2,499	875	-612	4,846
Accumulated Other Comprehensive Income (Loss), ending balance	13,059	-59,666	13,059	-59,666
Accumulated Defined Benefit Plans Adjustment	'	'	'	'
Accumulated Other Comprehensive Income (Loss) [Line Items]	'	'	'	'
Accumulated Other Comprehensive Income (Loss), beginning balance	-21,330	-75,737	-75,032	-77,246
Other Comprehensive Income (Loss) before Reclassifications	12,147	0	63,599	-1,264
Amounts Reclassified from Accumulated Other Comprehensive Income (Loss)	-205	705	2,045	3,478
Accumulated Other Comprehensive Income (Loss), ending balance	-9,388	-75,032	-9,388	-75,032
Accumulated Net Unrealized Investment Gain (Loss)	'	'	'	'
Accumulated Other Comprehensive Income (Loss) [Line Items]	'	'	'	'
Accumulated Other Comprehensive Income (Loss), beginning balance	36,240	22,194	27,858	20,049
Other Comprehensive Income (Loss) before Reclassifications	799	5,543	9,738	6,695
Amounts Reclassified from Accumulated Other Comprehensive Income (Loss)	-2,309	121	-2,866	1,114
Accumulated Other Comprehensive Income (Loss), ending balance	34,730	27,858	34,730	27,858
Accumulated Net Gain (Loss) from Designated or Qualifying Cash Flow Hedges	'	'	'	'
Accumulated Other Comprehensive Income (Loss) [Line Items]	'	'	'	'
Accumulated Other Comprehensive Income (Loss), beginning balance	-12,298	-12,541	-12,492	-12,746
Other Comprehensive Income (Loss) before Reclassifications	0	0	0	0
Amounts Reclassified from Accumulated Other Comprehensive Income (Loss)	15	49	209	254
Accumulated Other Comprehensive Income (Loss), ending balance	($12,283)	($12,492)	($12,283)	($12,492)

Accumulated_Other_Comprehensiv3

Accumulated Other Comprehensive Income Amounts Reclassified (Details) (USD $)	3 Months Ended				12 Months Ended
In Thousands, unless otherwise specified	Mar. 31, 2014		Mar. 31, 2013		Mar. 31, 2014		Mar. 31, 2013
Accumulated Other Comprehensive Income (Loss) [Line Items]	'		'		'		'
Prior service benefit	$1,459		$1,400		$5,619		$5,719
Unrealized Losses on Available-for-Sale Securities included in Pre-Tax Income	0		0		0		479
Interest on long-term debt and revolving credit facility	-11,822		-11,820		-47,714		-45,516
Income tax expense	1,473		3,315		41,813		49,517
Net income (loss)	4,579		7,608		85,304		94,888
Reclassification out of Accumulated Other Comprehensive Income	'		'		'		'
Accumulated Other Comprehensive Income (Loss) [Line Items]	'		'		'		'
Net income (loss)	2,499		-875		612		-4,846
Reclassification out of Accumulated Other Comprehensive Income | Accumulated Defined Benefit Plans Adjustment	'		'		'		'
Accumulated Other Comprehensive Income (Loss) [Line Items]	'		'		'		'
Prior service benefit	1,459	[1]	1,400	[1]	5,619	[1]	5,719	[1]
Net Loss	-1,123	[1]	-2,675	[1]	-8,920	[1]	-11,521	[1]
Income (Loss) before income tax	336	[1]	-1,275	[1]	-3,301	[1]	-5,802	[1]
Income tax expense	-131		570		1,256		2,324
Net income (loss)	205	[1]	-705	[1]	-2,045	[1]	-3,478	[1]
Reclassification out of Accumulated Other Comprehensive Income | Accumulated Net Unrealized Investment Gain (Loss)	'		'		'		'
Accumulated Other Comprehensive Income (Loss) [Line Items]	'		'		'		'
Net Realized Gain (Loss) on Sale of Securities	2,865		-158		3,576		-934
Unrealized Losses on Available-for-Sale Securities included in Pre-Tax Income	0		0		0		-479
Income (Loss) before income tax	2,865		-158		3,576		-1,413
Income tax expense	-556		37		-710		299
Net income (loss)	2,309		-121		2,866		-1,114
Reclassification out of Accumulated Other Comprehensive Income | Accumulated Net Gain (Loss) from Designated or Qualifying Cash Flow Hedges	'		'		'		'
Accumulated Other Comprehensive Income (Loss) [Line Items]	'		'		'		'
Interest on long-term debt and revolving credit facility	-107		-101		-417		-392
Income (Loss) before income tax	-107		-101		-417		-392
Income tax expense	92		52		208		138
Net income (loss)	($15)		($49)		($209)		($254)
[1]	These items are included in the computation of net periodic benefit cost. See Note H, Employee Benefits, for additional information.

Regulation_Narrative_Details

Regulation (Narrative) (Details) (USD $)

3 Months Ended

0 Months Ended

0 Months Ended

0 Months Ended

3 Months Ended

0 Months Ended

3 Months Ended

Mar. 31, 2014

Sep. 07, 2013

Jan. 14, 2014

Oct. 30, 2013

Sep. 07, 2013

Oct. 29, 2013

Nov. 15, 2013

Nov. 14, 2013

Jan. 31, 2013

Sep. 09, 2013

Sep. 27, 2013

Sep. 07, 2013

Sep. 07, 2013

Sep. 07, 2013

Sep. 07, 2013

Oct. 30, 2013

Nov. 15, 2013

Mar. 31, 2014

Mar. 31, 2014

Mar. 31, 2014

Mar. 31, 2014

Sep. 07, 2013

Sep. 07, 2013

Mar. 31, 2014

Apr. 15, 2014

PUCT

NMPRC

NMPRC

NMPRC

NMPRC

FERC

FERC

FERC

PUCT Docket No. 41803

PUCT Docket No. 41852

MPS To Caliente Transmission Line

MPS In & Out Transmission Line

Caliente - Coyote Transmission Line

MPS To Montwood Transmission Line

Nuclear Fuel Financing

Nuclear Fuel Financing

Montana Power Station

Montana Power Station

Montana Power Station

Montana Power Station

Montana Power Station

Montana Power Station

Minimum

Subsequent Event

MW

MW

PUCT Docket No. 41360

PUCT Docket No. 41359

PUCT Docket No. 41359

PUCT Docket No. 41809

NMPRC

FERC

PUCT

NMPRC

Phase I of Construction

Phase I of Construction

Phase II of Construction

Phase II of Construction

PUCT Docket No. 42384

kV

kV

kV

kV

PUCT

NMPRC

PUCT

NMPRC

Fixed Fuel Factor Revision Period, in Months

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'4 months

'

Increase (Decrease) In Fixed Fuel Factor

'

'

'

'

'

'

'

'

'

$16,900,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

$10,700,000

Percent Increase (Decrease) In Fixed Fuel Factor

'

'

'

'

'

'

'

'

'

12.20%

'

'

'

'

'

'

'

'

'

'

'

'

'

'

6.90%

Reconcilable Fuel Expense

'

'

'

'

'

'

'

'

'

'

545,300,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Fuel Reconciliation Period

'

'

'

'

'

'

'

'

'

'

'45 months

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Rewards For Operations Requested

'

'

'

'

'

'

'

'

'

'

3,400,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Number of power generation units authorized to be constructed

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

2

2

2

2

'

'

Number of Power Generation Units

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

4

4

'

'

'

'

'

'

Electric Capacity

'

88

'

'

88

'

'

'

'

'

'

115

115

115

115

'

'

'

'

'

'

'

'

'

'

Number Of Transmission Lines

3

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Line of Credit Facility, Current Borrowing Capacity

'

'

300,000,000

400,000,000

'

300,000,000

400,000,000

300,000,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Line of Credit Facility, Expiration Period

'

'

'

'4 years

'

'

'4 years

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Debt Instrument, Face Amount

'

'

'

300,000,000

'

'

300,000,000

'

'

'

'

'

'

'

'

50,000,000

50,000,000

'

'

'

'

'

'

'

'

Line of Credit Facility, Increase (Decrease), Net

'

'

100,000,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Line of Credit Facility, Maximum Borrowing Capacity

'

'

400,000,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Line of Credit Facility, Expiration Date

'

'

14-Jan-19

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Line of Credit renewal option, renewal times

'

'

2

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Line of Credit renewal term, year

'

'

'1 year

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Refund Related to Dispute

'

'

'

'

'

'

'

'

$1,900,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Common_Stock_Narrative_Details

Common Stock (Narrative) (Details) (USD $)	3 Months Ended		12 Months Ended
In Millions, unless otherwise specified	Mar. 31, 2014	Mar. 31, 2013	Mar. 31, 2014	Mar. 31, 2013
Dividends, Common Stock, Cash	$10.70	$10.10	$42.70	$40.10

Common_Stock_Basic_And_Diluted

Common Stock (Basic And Diluted Earnings Per Share) (Details) (USD $)	3 Months Ended		12 Months Ended
In Thousands, except Share data, unless otherwise specified	Mar. 31, 2014	Mar. 31, 2013	Mar. 31, 2014	Mar. 31, 2013
Class of Stock Disclosures [Abstract]	'	'	'	'
Basic number of common shares outstanding	40,149,083	40,078,061	40,132,106	40,015,380
Dilutive effect of unvested performance awards	0	0	12,053	50,206
Dilutive effect of stock options	0	0	0	9,234
Diluted number of common shares outstanding	40,149,083	40,078,061	40,144,159	40,074,820
Net income	$4,615	$7,634	$85,564	$95,136
Income allocated to participating restricted stock	-36	-26	-260	-248
Net income available to common shareholders, basic	4,579	7,608	85,304	94,888
Income reallocated to participating restricted stock	-36	-26	-260	-247
Net income available to common shareholders, diluted	$4,579	$7,608	$85,304	$94,889
Earnings Per Share, Basic, Distributed	$0.27	$0.25	$1.06	$1
Earnings Per Share, Basic, Undistributed	($0.16)	($0.06)	$1.07	$1.37
Basic net income per common share	$0.11	$0.19	$2.13	$2.37
Earnings Per Share, Diluted, Distributed	$0.27	$0.25	$1.06	$1
Earnings Per Sare, Diluted, Undistributed	($0.16)	($0.06)	$1.06	$1.37
Diluted net income per common share	$0.11	$0.19	$2.12	$2.37

Common_Stock_Antidilutive_Secu

Common Stock (Antidilutive Securities Excluded From Computation Of Earnings Per Share) (Details)	3 Months Ended				12 Months Ended
	Mar. 31, 2014		Mar. 31, 2013		Mar. 31, 2014		Mar. 31, 2013
Performance shares payout based upon performance	0		0		0		0
Performance shares payout level	100.00%		100.00%		100.00%		100.00%
Restricted Stock	'		'		'		'
Antidilutive Securities Excluded from the Computation of Diluted Earnings Per Share, Amount	79,413		56,101		57,017		44,253
Performance Shares	'		'		'		'
Antidilutive Securities Excluded from the Computation of Diluted Earnings Per Share, Amount	128,508	[1]	124,997	[1]	90,384	[1]	78,112	[1]
[1]	Certain performance shares were excluded from the computation of diluted earnings per share as no payouts would have been required based upon performance at the end of each corresponding period.

Income_Taxes_Effective_Income_

Income Taxes (Effective Income Tax Rates) (Details)	3 Months Ended		12 Months Ended
	Mar. 31, 2014	Mar. 31, 2013	Mar. 31, 2014	Mar. 31, 2013
Consolidated effective tax rate	24.20%	30.30%	32.80%	34.20%
Federal statutory tax rate	35.00%	35.00%	35.00%	35.00%
Income tax rate capital gains	20.00%	'	'	'

Commitments_Contingencies_And_1

Commitments, Contingencies And Uncertainties (Power Purchase and Sale Contracts) (Details) (Macho Springs Solar)	3 Months Ended
	Mar. 31, 2014
	MW
Macho Springs Solar	'
Long-term Contract for Purchase of Electric Power [Line Items]	'
Projected Plant Commercial Operation Date	31-May-14
Plant Capacity	50

Commitments_Contingencies_And_2

Commitments, Contingencies And Uncertainties (Narrative) (Details) (USD $)	3 Months Ended
In Millions, unless otherwise specified	Mar. 31, 2014
Loss Contingencies [Line Items]	'
GHG Emission Level, Percentage	17.00%
Four Corners Coal Plant Participants	'
Loss Contingencies [Line Items]	'
Public Utilities, Assessed Coal Severance Surtax Penalty and Interest	$30
Four Corners Generating Station	'
Loss Contingencies [Line Items]	'
Accrual for Environmental Loss Contingencies	0.5
Public Utilities, Assessed Coal Severance Surtax Penalty and Interest	1.5
Four Corners Generating Station	'
Loss Contingencies [Line Items]	'
Cost of Pollution Control Equipment	$39
Four Corners Generating Station	'
Loss Contingencies [Line Items]	'
Date participation is ceased	6-Jul-16

Employee_Benefits_Retirement_P

Employee Benefits (Retirement Plans And Other Postretirement Benefits) (Details) (USD $)	3 Months Ended		12 Months Ended
In Thousands, unless otherwise specified	Mar. 31, 2014	Mar. 31, 2013	Mar. 31, 2014	Mar. 31, 2013
Retirement Income Plan	'	'	'	'
Defined Benefit Plan Disclosure [Line Items]	'	'	'	'
Service cost	$2,173	$2,400	$9,100	$9,004
Interest cost	3,870	3,400	14,084	13,579
Expected return on plan assets	-4,680	-4,275	-17,513	-15,108
Amortization of prior service (benefit) cost	-259	25	-187	113
Amortization of net (gain) loss	1,773	2,675	10,196	11,066
Net periodic benefit cost (benefit)	2,877	4,225	15,680	18,654
Other Postretirement Benefit Plans, Defined Benefit	'	'	'	'
Defined Benefit Plan Disclosure [Line Items]	'	'	'	'
Service cost	700	1,100	3,443	4,408
Interest cost	1,125	1,375	4,906	5,611
Expected return on plan assets	-525	-475	-2,001	-1,754
Amortization of prior service (benefit) cost	-1,200	-1,425	-5,432	-5,832
Amortization of net (gain) loss	-650	0	-1,276	455
Net periodic benefit cost (benefit)	($550)	$575	($360)	$2,888

Employee_Benefits_Narrative_De

Employee Benefits (Narrative) (Details) (USD $)	Feb. 28, 2014	Dec. 31, 2013	Feb. 28, 2014	Dec. 31, 2013	Mar. 31, 2014	Feb. 28, 2014
	Retirement Income Plan	Retirement Income Plan	Excess Benefit Plan	Excess Benefit Plan	Retirement Plans	Retirement Plans
Defined Benefit Plan Disclosure [Line Items]	'	'	'	'	'	'
Defined Benefit Plan, Employer Contribution	'	'	'	'	$3,500,000	'
Defined Benefit Plan, Expected Contributions in Current Fiscal Year	'	'	'	'	8,700,000	'
Defined Benefit Plan, Discount Rate	4.60%	4.90%	4.50%	4.90%	'	'
Defined Benefit Plan, Decrease in Accumulated Benefit Obligation due to Plan Amendment	'	'	'	'	'	19,700,000
Increase in Other Comprehensive Income Arising During Period, before Tax	'	'	'	'	'	19,700,000
Defined Benefit Plan Increase in Expected Future Benefit Payments Next Five Years	'	'	'	'	'	17,200,000
Defined Benefit Plan, Decrease in Net Periodic Benefit Cost due to Change of Actuarial Assumptions and Plan Amendment	'	'	'	'	'	$8,400,000

Recovered_Sheet1

Financial Instruments and Investments (Carrying Amount and Fair Value Amounts) (Details) (USD $)	Mar. 31, 2014		Dec. 31, 2013
In Thousands, unless otherwise specified
Carrying (Reported) Amount, Fair Value Disclosure	'		'
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]	'		'
Debt Instrument, Fair Value Disclosure	$1,045,594		$1,013,972
Estimate of Fair Value, Fair Value Disclosure	'		'
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]	'		'
Debt Instrument, Fair Value Disclosure	1,110,264		1,058,707
Pollution Control Bonds | Carrying (Reported) Amount, Fair Value Disclosure	'		'
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]	'		'
Debt Instrument, Fair Value Disclosure	193,135		193,135
Pollution Control Bonds | Estimate of Fair Value, Fair Value Disclosure	'		'
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]	'		'
Debt Instrument, Fair Value Disclosure	202,897		193,990
Senior Notes | Carrying (Reported) Amount, Fair Value Disclosure	'		'
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]	'		'
Debt Instrument, Fair Value Disclosure	696,508		696,485
Senior Notes | Estimate of Fair Value, Fair Value Disclosure	'		'
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]	'		'
Debt Instrument, Fair Value Disclosure	744,856		734,515
RGRT Senior Notes | Carrying (Reported) Amount, Fair Value Disclosure	'		'
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]	'		'
Debt Instrument, Fair Value Disclosure	110,000	[1]	110,000	[1]
RGRT Senior Notes | Estimate of Fair Value, Fair Value Disclosure	'		'
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]	'		'
Debt Instrument, Fair Value Disclosure	116,560	[1]	115,850	[1]
Revolving Credit Facility | Carrying (Reported) Amount, Fair Value Disclosure	'		'
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]	'		'
Debt Instrument, Fair Value Disclosure	45,951	[1]	14,352	[1]
Revolving Credit Facility | Estimate of Fair Value, Fair Value Disclosure	'		'
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]	'		'
Debt Instrument, Fair Value Disclosure	$45,951	[1]	$14,352	[1]
[1]	Nuclear fuel financing as of MarchB 31, 2014 and DecemberB 31, 2013 is funded through the $110 million RGRT Senior Notes and $20.0 million and $14.4 million, respectively under the RCF. As of MarchB 31, 2014, $26.0 million was outstanding under the RCF for working capital or general corporate purposes. As of DecemberB 31, 2013, no amount was outstanding under the RCF for working capital or general corporate purposes. The interest rate on the Companybs borrowings under the RCF is reset throughout the quarter reflecting current market rates. Consequently, the carrying value approximates fair value.

Financial_Instruments_And_Inve2

Financial Instruments And Investments (Long-Term Debt and Short-Term Borrowings - Narratives) (Details) (USD $)	Mar. 31, 2014	Dec. 31, 2013	Mar. 31, 2014	Dec. 31, 2013	Mar. 31, 2014	Dec. 31, 2013	Aug. 18, 2010
In Thousands, unless otherwise specified			Nuclear Fuel Financing	Nuclear Fuel Financing	Working Capital and General Purpose	Working Capital and General Purpose	RGRT Senior Notes
Financial Instruments and Investments [Line Items]	'	'	'	'	'	'	'
Debt Instrument, Face Amount	'	'	'	'	'	'	$110,000
Line of Credit Facility, Amount Outstanding	'	'	20,000	14,400	26,000	0	'
Decommissioning Fund Investments	$217,509	$214,095	'	'	'	'	'

Financial_Instruments_And_Inve3

Financial Instruments And Investments (Marketable Securities Fair Value And Unrealized Losses) (Details) (USD $)	3 Months Ended		12 Months Ended
In Thousands, unless otherwise specified	Mar. 31, 2014		Dec. 31, 2013
	securities		securities
Financial Instruments and Investments [Line Items]	'		'
Marketable Securities Fair Value Less than 12 Months	$17,423	[1]	$32,433	[2]
Marketable Securities Unrealized Losses Less Than 12 Months	-318	[1]	-971	[2]
Marketable Securities Fair Value 12 Months or Longer	32,922	[1]	20,970	[2]
Marketable Securities Unrealized Losses 12 Months or Longer	-1,758	[1]	-1,492	[2]
Marketable Securities Fair Value Total	50,345	[1]	53,403	[2]
Marketable Securities Unrealized Losses Total	-2,076	[1]	-2,463	[2]
Number of securities	119		122
Debt Securities	'		'
Financial Instruments and Investments [Line Items]	'		'
Marketable Securities Fair Value Less than 12 Months	15,809	[1]	30,128	[2]
Marketable Securities Unrealized Losses Less Than 12 Months	-196	[1]	-845	[2]
Marketable Securities Fair Value 12 Months or Longer	32,922	[1]	20,970	[2]
Marketable Securities Unrealized Losses 12 Months or Longer	-1,758	[1]	-1,492	[2]
Marketable Securities Fair Value Total	48,731	[1]	51,098	[2]
Marketable Securities Unrealized Losses Total	-1,954	[1]	-2,337	[2]
Collateralized Mortgage Backed Securities	'		'
Financial Instruments and Investments [Line Items]	'		'
Marketable Securities Fair Value Less than 12 Months	4,667	[1]	6,444	[2]
Marketable Securities Unrealized Losses Less Than 12 Months	-28	[1]	-169	[2]
Marketable Securities Fair Value 12 Months or Longer	2,457	[1]	1,421	[2]
Marketable Securities Unrealized Losses 12 Months or Longer	-170	[1]	-119	[2]
Marketable Securities Fair Value Total	7,124	[1]	7,865	[2]
Marketable Securities Unrealized Losses Total	-198	[1]	-288	[2]
U.S. Government Bonds	'		'
Financial Instruments and Investments [Line Items]	'		'
Marketable Securities Fair Value Less than 12 Months	1,548	[1]	8,114	[2]
Marketable Securities Unrealized Losses Less Than 12 Months	-1	[1]	-245	[2]
Marketable Securities Fair Value 12 Months or Longer	16,128	[1]	10,866	[2]
Marketable Securities Unrealized Losses 12 Months or Longer	-893	[1]	-840	[2]
Marketable Securities Fair Value Total	17,676	[1]	18,980	[2]
Marketable Securities Unrealized Losses Total	-894	[1]	-1,085	[2]
Municipal Bonds	'		'
Financial Instruments and Investments [Line Items]	'		'
Marketable Securities Fair Value Less than 12 Months	6,860	[1]	12,286	[2]
Marketable Securities Unrealized Losses Less Than 12 Months	-101	[1]	-335	[2]
Marketable Securities Fair Value 12 Months or Longer	13,038	[1]	7,782	[2]
Marketable Securities Unrealized Losses 12 Months or Longer	-651	[1]	-479	[2]
Marketable Securities Fair Value Total	19,898	[1]	20,068	[2]
Marketable Securities Unrealized Losses Total	-752	[1]	-814	[2]
Corporate Debt Securities	'		'
Financial Instruments and Investments [Line Items]	'		'
Marketable Securities Fair Value Less than 12 Months	2,734	[1]	3,284	[2]
Marketable Securities Unrealized Losses Less Than 12 Months	-66	[1]	-96	[2]
Marketable Securities Fair Value 12 Months or Longer	1,299	[1]	901	[2]
Marketable Securities Unrealized Losses 12 Months or Longer	-44	[1]	-54	[2]
Marketable Securities Fair Value Total	4,033	[1]	4,185	[2]
Marketable Securities Unrealized Losses Total	-110	[1]	-150	[2]
Equity Securities	'		'
Financial Instruments and Investments [Line Items]	'		'
Marketable Securities Fair Value Less than 12 Months	1,614	[1]	2,305	[2]
Marketable Securities Unrealized Losses Less Than 12 Months	-122	[1]	-126	[2]
Marketable Securities Fair Value 12 Months or Longer	0	[1]	0	[2]
Marketable Securities Unrealized Losses 12 Months or Longer	0	[1]	0	[2]
Marketable Securities Fair Value Total	1,614	[1]	2,305	[2]
Marketable Securities Unrealized Losses Total	($122)	[1]	($126)	[2]
[1]	Includes approximately 119 securities.
[2]	Includes approximately 122 securities.

Financial_Instruments_And_Inve4

Financial Instruments And Investments (Unrecognized Gross Unrealized Gains And The Fair Value) (Details) (USD $)	Mar. 31, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Financial Instruments and Investments [Line Items]	'	'
Available-for-sale Securities, Unrealized Gain Position, Fair Value	$167,164	$160,692
Available-for-sale Securities, Gross Unrealized Gain	45,483	47,741
Debt Securities	'	'
Financial Instruments and Investments [Line Items]	'	'
Available-for-sale Securities, Unrealized Gain Position, Fair Value	39,990	34,158
Available-for-sale Securities, Gross Unrealized Gain	1,846	1,515
Collateralized Mortgage Backed Securities	'	'
Financial Instruments and Investments [Line Items]	'	'
Available-for-sale Securities, Unrealized Gain Position, Fair Value	10,276	9,929
Available-for-sale Securities, Gross Unrealized Gain	489	433
U.S. Government Bonds	'	'
Financial Instruments and Investments [Line Items]	'	'
Available-for-sale Securities, Unrealized Gain Position, Fair Value	9,719	6,258
Available-for-sale Securities, Gross Unrealized Gain	180	126
Municipal Bonds	'	'
Financial Instruments and Investments [Line Items]	'	'
Available-for-sale Securities, Unrealized Gain Position, Fair Value	10,237	8,783
Available-for-sale Securities, Gross Unrealized Gain	528	450
Corporate Debt Securities	'	'
Financial Instruments and Investments [Line Items]	'	'
Available-for-sale Securities, Unrealized Gain Position, Fair Value	9,758	9,188
Available-for-sale Securities, Gross Unrealized Gain	649	506
Equity Securities	'	'
Financial Instruments and Investments [Line Items]	'	'
Available-for-sale Securities, Unrealized Gain Position, Fair Value	105,835	103,808
Available-for-sale Securities, Gross Unrealized Gain	43,402	43,145
Common Collective Trust - Equity Funds	'	'
Financial Instruments and Investments [Line Items]	'	'
Available-for-sale Securities, Unrealized Gain Position, Fair Value	16,891	0
Available-for-sale Securities, Gross Unrealized Gain	235	0
Equity Mutual Funds	'	'
Financial Instruments and Investments [Line Items]	'	'
Available-for-sale Securities, Unrealized Gain Position, Fair Value	0	16,802
Available-for-sale Securities, Gross Unrealized Gain	0	3,081
Cash and Cash Equivalents	'	'
Financial Instruments and Investments [Line Items]	'	'
Available-for-sale Securities, Unrealized Gain Position, Fair Value	4,448	5,924
Available-for-sale Securities, Gross Unrealized Gain	$0	$0

Financial_Instruments_And_Inve5

Financial Instruments And Investments (Contractual Year For Maturity Of Available-For-Sale Securities ) (Details) (USD $)	3 Months Ended
In Thousands, unless otherwise specified	Mar. 31, 2014
Schedule of Available-for-sale Securities [Line Items]	'
Contractual Maturity Due For, Mortgaged Backed Securities	'10 years
Municipal Bonds	'
Schedule of Available-for-sale Securities [Line Items]	'
Total	30,135
2014	976
2015 through 2018	13,279
2019 through 2023	12,562
2024 and Beyond	3,318
Corporate Debt Obligations	'
Schedule of Available-for-sale Securities [Line Items]	'
Total	13,791
2014	317
2015 through 2018	3,324
2019 through 2023	5,963
2024 and Beyond	4,187
U.S. Government Bonds	'
Schedule of Available-for-sale Securities [Line Items]	'
Total	27,395
2014	1,210
2015 through 2018	14,347
2019 through 2023	6,434
2024 and Beyond	5,404
Maximum	'
Schedule of Available-for-sale Securities [Line Items]	'
Debt Instrument, Expected Weighted Average Maturity Year	'8 years
Minimum	'
Schedule of Available-for-sale Securities [Line Items]	'
Debt Instrument, Expected Weighted Average Maturity Year	'3 years

Financial_Instruments_And_Inve6

Financial Instruments And Investments (Unrealized Holding Losses Included In Pre-Tax Income) (Details) (USD $)	3 Months Ended		12 Months Ended
In Thousands, unless otherwise specified	Mar. 31, 2014	Mar. 31, 2013	Mar. 31, 2014	Mar. 31, 2013
Financial Instruments And Investments [Abstract]	'	'	'	'
Unrealized losses included in pre-tax income	$0	$0	$0	($479)

Financial_Instruments_And_Inve7

Financial Instruments And Investments (Sale Of Securities And The Related Effects On Pre-Tax Income ) (Details) (USD $)	3 Months Ended		12 Months Ended
In Thousands, unless otherwise specified	Mar. 31, 2014	Mar. 31, 2013	Mar. 31, 2014	Mar. 31, 2013
Investment [Line Items]	'	'	'	'
Proceeds from sales of available-for-sale securities	$28,827	$10,907	$74,067	$89,870
Gross realized gains included in pre-tax income	3,014	39	3,961	1,128
Gross realized losses included in pre-tax income	-149	-197	-385	-2,062
Other than temporary impairment losses, recognized in earnings before tax	0	0	0	-479
Net unrealized holding gains (losses) included in accumulated other comprehensive income	998	6,793	11,904	8,562
Net gains (losses) in pre-tax income	2,865	-158	3,576	-1,413
Net gains (losses) in other comprehensive income	($1,867)	$6,951	$8,328	$9,975

Financial_Instruments_And_Inve8

Financial Instruments And Investments (Company's Decommissioning Trust Funds And Investments In Debt Securities) (Details) (USD $)	Mar. 31, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Decommissioning Fund Investments	'	'
Financial Instruments and Investments [Line Items]	'	'
Available-for-sale Securities	$217,509	$214,095
Decommissioning Fund Investments | Quoted Prices In Active Markets For Identical Assets (Level 1)	'	'
Financial Instruments and Investments [Line Items]	'	'
Available-for-sale Securities	139,292	154,077
Decommissioning Fund Investments | Significant Other Observable Inputs (Level 2)	'	'
Financial Instruments and Investments [Line Items]	'	'
Available-for-sale Securities	78,217	60,018
Decommissioning Fund Investments | Significant Unobservable Inputs (Level 3)	'	'
Financial Instruments and Investments [Line Items]	'	'
Available-for-sale Securities	0	0
Debt Securities	'	'
Financial Instruments and Investments [Line Items]	'	'
Investments in Debt Securities	1,503	1,555
Debt Securities | Quoted Prices In Active Markets For Identical Assets (Level 1)	'	'
Financial Instruments and Investments [Line Items]	'	'
Investments in Debt Securities	0	0
Debt Securities | Significant Other Observable Inputs (Level 2)	'	'
Financial Instruments and Investments [Line Items]	'	'
Investments in Debt Securities	0	0
Debt Securities | Significant Unobservable Inputs (Level 3)	'	'
Financial Instruments and Investments [Line Items]	'	'
Investments in Debt Securities	1,503	1,555
Debt Securities | Decommissioning Fund Investments	'	'
Financial Instruments and Investments [Line Items]	'	'
Available-for-sale Securities	88,721	85,256
Debt Securities | Decommissioning Fund Investments | Quoted Prices In Active Markets For Identical Assets (Level 1)	'	'
Financial Instruments and Investments [Line Items]	'	'
Available-for-sale Securities	27,395	25,238
Debt Securities | Decommissioning Fund Investments | Significant Other Observable Inputs (Level 2)	'	'
Financial Instruments and Investments [Line Items]	'	'
Available-for-sale Securities	61,326	60,018
Debt Securities | Decommissioning Fund Investments | Significant Unobservable Inputs (Level 3)	'	'
Financial Instruments and Investments [Line Items]	'	'
Available-for-sale Securities	0	0
U.S. Government Bonds | Decommissioning Fund Investments	'	'
Financial Instruments and Investments [Line Items]	'	'
Available-for-sale Securities	27,395	25,238
U.S. Government Bonds | Decommissioning Fund Investments | Quoted Prices In Active Markets For Identical Assets (Level 1)	'	'
Financial Instruments and Investments [Line Items]	'	'
Available-for-sale Securities	27,395	25,238
U.S. Government Bonds | Decommissioning Fund Investments | Significant Other Observable Inputs (Level 2)	'	'
Financial Instruments and Investments [Line Items]	'	'
Available-for-sale Securities	0	0
U.S. Government Bonds | Decommissioning Fund Investments | Significant Unobservable Inputs (Level 3)	'	'
Financial Instruments and Investments [Line Items]	'	'
Available-for-sale Securities	0	0
Collateralized Mortgage Backed Securities | Decommissioning Fund Investments	'	'
Financial Instruments and Investments [Line Items]	'	'
Available-for-sale Securities	17,400	17,794
Collateralized Mortgage Backed Securities | Decommissioning Fund Investments | Quoted Prices In Active Markets For Identical Assets (Level 1)	'	'
Financial Instruments and Investments [Line Items]	'	'
Available-for-sale Securities	0	0
Collateralized Mortgage Backed Securities | Decommissioning Fund Investments | Significant Other Observable Inputs (Level 2)	'	'
Financial Instruments and Investments [Line Items]	'	'
Available-for-sale Securities	17,400	17,794
Collateralized Mortgage Backed Securities | Decommissioning Fund Investments | Significant Unobservable Inputs (Level 3)	'	'
Financial Instruments and Investments [Line Items]	'	'
Available-for-sale Securities	0	0
Municipal Bonds | Decommissioning Fund Investments	'	'
Financial Instruments and Investments [Line Items]	'	'
Available-for-sale Securities	30,135	28,851
Municipal Bonds | Decommissioning Fund Investments | Quoted Prices In Active Markets For Identical Assets (Level 1)	'	'
Financial Instruments and Investments [Line Items]	'	'
Available-for-sale Securities	0	0
Municipal Bonds | Decommissioning Fund Investments | Significant Other Observable Inputs (Level 2)	'	'
Financial Instruments and Investments [Line Items]	'	'
Available-for-sale Securities	30,135	28,851
Municipal Bonds | Decommissioning Fund Investments | Significant Unobservable Inputs (Level 3)	'	'
Financial Instruments and Investments [Line Items]	'	'
Available-for-sale Securities	0	0
Corporate Debt Securities | Decommissioning Fund Investments	'	'
Financial Instruments and Investments [Line Items]	'	'
Available-for-sale Securities	13,791	13,373
Corporate Debt Securities | Decommissioning Fund Investments | Quoted Prices In Active Markets For Identical Assets (Level 1)	'	'
Financial Instruments and Investments [Line Items]	'	'
Available-for-sale Securities	0	0
Corporate Debt Securities | Decommissioning Fund Investments | Significant Other Observable Inputs (Level 2)	'	'
Financial Instruments and Investments [Line Items]	'	'
Available-for-sale Securities	13,791	13,373
Corporate Debt Securities | Decommissioning Fund Investments | Significant Unobservable Inputs (Level 3)	'	'
Financial Instruments and Investments [Line Items]	'	'
Available-for-sale Securities	0	0
Equity Securities | Decommissioning Fund Investments	'	'
Financial Instruments and Investments [Line Items]	'	'
Available-for-sale Securities	107,449	106,113
Equity Securities | Decommissioning Fund Investments | Quoted Prices In Active Markets For Identical Assets (Level 1)	'	'
Financial Instruments and Investments [Line Items]	'	'
Available-for-sale Securities	107,449	106,113
Equity Securities | Decommissioning Fund Investments | Significant Other Observable Inputs (Level 2)	'	'
Financial Instruments and Investments [Line Items]	'	'
Available-for-sale Securities	0	0
Equity Securities | Decommissioning Fund Investments | Significant Unobservable Inputs (Level 3)	'	'
Financial Instruments and Investments [Line Items]	'	'
Available-for-sale Securities	0	0
Common Collective Trust - Equity Funds | Decommissioning Fund Investments	'	'
Financial Instruments and Investments [Line Items]	'	'
Available-for-sale Securities	16,891	'
Common Collective Trust - Equity Funds | Decommissioning Fund Investments | Quoted Prices In Active Markets For Identical Assets (Level 1)	'	'
Financial Instruments and Investments [Line Items]	'	'
Available-for-sale Securities	0	'
Common Collective Trust - Equity Funds | Decommissioning Fund Investments | Significant Other Observable Inputs (Level 2)	'	'
Financial Instruments and Investments [Line Items]	'	'
Available-for-sale Securities	16,891	'
Common Collective Trust - Equity Funds | Decommissioning Fund Investments | Significant Unobservable Inputs (Level 3)	'	'
Financial Instruments and Investments [Line Items]	'	'
Available-for-sale Securities	0	'
Equity Mutual Funds | Decommissioning Fund Investments	'	'
Financial Instruments and Investments [Line Items]	'	'
Available-for-sale Securities	'	16,802
Equity Mutual Funds | Decommissioning Fund Investments | Quoted Prices In Active Markets For Identical Assets (Level 1)	'	'
Financial Instruments and Investments [Line Items]	'	'
Available-for-sale Securities	'	16,802
Equity Mutual Funds | Decommissioning Fund Investments | Significant Other Observable Inputs (Level 2)	'	'
Financial Instruments and Investments [Line Items]	'	'
Available-for-sale Securities	'	0
Equity Mutual Funds | Decommissioning Fund Investments | Significant Unobservable Inputs (Level 3)	'	'
Financial Instruments and Investments [Line Items]	'	'
Available-for-sale Securities	'	0
Cash and Cash Equivalents | Decommissioning Fund Investments	'	'
Financial Instruments and Investments [Line Items]	'	'
Available-for-sale Securities	4,448	5,924
Cash and Cash Equivalents | Decommissioning Fund Investments | Quoted Prices In Active Markets For Identical Assets (Level 1)	'	'
Financial Instruments and Investments [Line Items]	'	'
Available-for-sale Securities	4,448	5,924
Cash and Cash Equivalents | Decommissioning Fund Investments | Significant Other Observable Inputs (Level 2)	'	'
Financial Instruments and Investments [Line Items]	'	'
Available-for-sale Securities	0	0
Cash and Cash Equivalents | Decommissioning Fund Investments | Significant Unobservable Inputs (Level 3)	'	'
Financial Instruments and Investments [Line Items]	'	'
Available-for-sale Securities	$0	$0