El Paso Electric 10-Q 7 May 15 2015 Q1 Quarterly report Financial data

Document_And_Entity_Informatio

Document And Entity Information	3 Months Ended
	Mar. 31, 2015	Apr. 30, 2015
Document and Entity Information [Line Items]
Document Type	10-Q
Amendment Flag	FALSE
Document Period End Date	31-Mar-15
Document Fiscal Year Focus	2015
Document Fiscal Period Focus	Q1
Trading Symbol	ee
Entity Registrant Name	EL PASO ELECTRIC CO /TX/
Entity Central Index Key	31978
Current Fiscal Year End Date	-19
Entity Filer Category	Large Accelerated Filer
Entity Common Stock, Shares Outstanding		40,392,332

Balance_Sheets

Balance Sheets (USD $)	Mar. 31, 2015	Dec. 31, 2014
In Thousands, unless otherwise specified
Utility plant:
Electric plant in service	$3,515,280	$3,229,255
Less accumulated depreciation and amortization	-1,283,543	-1,266,672
Net plant in service	2,231,737	1,962,583
Construction work in progress	198,216	414,284
Nuclear fuel; includes fuel in process of $57,766 and $46,996, respectively	195,955	185,185
Less accumulated amortization	-84,295	-73,701
Net nuclear fuel	111,660	111,484
Net utility plant	2,541,613	2,488,351
Current assets:
Cash and cash equivalents	7,974	40,504
Accounts receivable, principally trade, net of allowance for doubtful accounts of $1,726 and $2,253, respectively	65,337	71,165
Accumulated deferred income taxes	18,103	13,957
Inventories, at cost	47,079	45,889
Under-collection of fuel revenues	0	10,253
Prepayments and other	18,842	12,213
Total current assets	157,335	193,981
Deferred charges and other assets:
Decommissioning trust funds	237,619	234,286
Regulatory assets	110,938	112,086
Other	31,007	30,597
Total deferred charges and other assets	379,564	376,969
Total assets	3,078,512	3,059,301
Capitalization:
Common stock, stated value $1 per share, 100,000,000 shares authorized, 65,704,207 and 65,725,246 shares issued, and 141,190 and 124,297 restricted shares, respectively	65,845	65,850
Capital in excess of stated value	318,584	318,515
Retained earnings	1,024,692	1,032,537
Accumulated other comprehensive loss, net of tax	-9,878	-8,001
Total stockholders equity subtotal before treasury stock	1,399,243	1,408,901
Treasury stock, 25,452,789 and 25,492,919 shares, respectively, at cost	-423,978	-424,647
Common stock equity	975,265	984,254
Long-term debt, net of current portion	1,134,205	1,134,179
Total capitalization	2,109,470	2,118,433
Current liabilities:
Current maturities of long-term debt	15,000	15,000
Short-term borrowings under the revolving credit facility	58,345	14,532
Accounts payable, principally trade	48,865	78,862
Taxes accrued	24,347	28,210
Interest accrued	16,872	12,758
Over-collection of fuel revenues	6,366	932
Other	23,805	24,715
Total current liabilities	193,600	175,009
Deferred Credits and Other Liabilities:
Accumulated deferred income taxes	484,564	474,154
Accrued pension liability	92,246	94,272
Accrued post-retirement benefit liability	60,717	59,342
Asset retirement obligation	76,290	74,577
Regulatory liabilities	25,175	26,099
Other	36,450	37,415
Total deferred credits and other liabilities	775,442	765,859
Commitments and contingencies
Total capitalization and liabilities	$3,078,512	$3,059,301

Balance_Sheets_Parenthetical

Balance Sheets Parenthetical (USD $)	Mar. 31, 2015	Dec. 31, 2014
In Thousands, except Share data, unless otherwise specified
Nuclear fuel; fuel in process	$57,766	$46,996
Allowance for Doubtful Accounts Receivable, Current	$1,726	$2,253
Common Stock, Par or Stated Value Per Share	$1	$1
Common Stock, Shares Authorized	100,000,000	100,000,000
Common Stock, Shares, Issued	65,704,207	65,725,246
Common stock, restricted shares	141,190	124,297
Treasury Stock, Shares	25,452,789	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, 2015	Mar. 31, 2014	Mar. 31, 2015	Mar. 31, 2014
Operating revenues	$163,746	$185,516	$895,755	$898,588
Energy expenses:
Fuel	37,729	51,586	237,148	233,955
Purchased and interchanged power	11,175	17,915	58,064	67,401
Cost of services, energy services	48,904	69,501	295,212	301,356
Operating revenues net of energy expenses	114,842	116,015	600,543	597,232
Other operating expenses:
Other operations	55,599	56,138	238,293	237,326
Maintenance	15,560	14,282	66,907	62,798
Depreciation and amortization	21,565	20,568	84,339	80,826
Taxes other than income taxes	14,158	15,362	61,546	60,327
Utilities operating expense	106,882	106,350	451,085	441,277
Operating income	7,960	9,665	149,458	155,955
Other income (deductions):
Allowance for equity funds used during construction	4,275	2,906	16,031	10,251
Investment and interest income, net	5,254	4,241	14,646	10,043
Miscellaneous non-operating income	180	1,517	2,738	2,425
Miscellaneous non-operating deductions	-491	-419	-4,271	-3,583
Nonoperating income (expense)	9,218	8,245	29,144	19,136
Interest charges (credits):
Interest on long-term debt and revolving credit facility	16,483	14,579	60,932	58,618
Other interest	163	173	1,240	455
Capitalized interest	-1,289	-1,246	-5,135	-5,243
Allowance for borrowed funds used during construction	-2,621	-1,684	-9,305	-6,116
Interest expense	12,736	11,822	47,732	47,714
Income before income taxes	4,442	6,088	130,870	127,377
Income tax expense	984	1,473	40,599	41,813
Net income	$3,458	$4,615	$90,271	$85,564
Basic earnings per share	$0.09	$0.11	$2.24	$2.13
Diluted earnings per share	$0.09	$0.11	$2.24	$2.12
Dividends declared per share of common stock	$0.28	$0.27	$1.12	$1.06
Weighted average number of shares outstanding	40,243,199	40,149,083	40,214,198	40,132,106
Weighted average number of shares and dilutive potential shares outstanding	40,266,674	40,149,083	40,240,793	40,144,159

Statements_Of_Comprehensive_Op

Statements Of Comprehensive Operations (USD $)	3 Months Ended		12 Months Ended
In Thousands, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014	Mar. 31, 2015	Mar. 31, 2014
Net income	$3,458	$4,615	$90,271	$85,564
Unrecognized pension and postretirement benefit costs:
Net gain (loss) arising during period	0	19,700	-74,028	102,664
Prior service benefit	0	0	34,200	97
Reclassification adjustments included in net income for amortization of:
Prior service benefit	-1,663	-1,459	-7,863	-5,619
Net loss	2,250	1,123	7,309	8,920
Net unrealized gains/losses on marketable securities:
Net holding gains arising during period	1,014	998	10,843	11,904
Reclassification adjustments for net gains included in net income	-3,745	-2,865	-8,230	-3,576
Net losses on cash flow hedges:
Reclassification adjustment for interest expense included in net income	114	107	445	417
Total other comprehensive income (loss) before income taxes	-2,030	17,604	-37,324	114,807
Income tax benefit (expense) related to items of other comprehensive income (loss):
Unrecognized pension and postretirement benefit costs	-331	-7,422	15,142	-40,418
Net unrealized losses (gains) on marketable securities	556	357	-561	-1,456
Losses on cash flow hedges	-72	-92	-194	-208
Total income tax benefit (expense)	153	-7,157	14,387	-42,082
Other comprehensive income (loss), net of tax	-1,877	10,447	-22,937	72,725
Comprehensive income	$1,581	$15,062	$67,334	$158,289

Statements_Of_Cash_Flows

Statements Of Cash Flows (USD $)	3 Months Ended
In Thousands, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014
Cash flows from operating activities:
Net income	$3,458	$4,615
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization of electric plant in service	21,565	20,568
Amortization of nuclear fuel	11,392	11,476
Deferred income taxes, net	6,255	761
Allowance for equity funds used during construction	-4,275	-2,906
Other amortization and accretion	4,499	4,141
Gain on sale of property, plant and equipment	0	-1,499
Net gains on sale of decommissioning trust funds	-3,745	-2,865
Other operating activities	132	54
Change in:
Accounts receivable	5,828	6,600
Inventories	-1,190	525
Net over-collection of fuel revenues	15,687	2,011
Prepayments and other	-2,691	-2,968
Accounts payable	-24,230	-8,958
Taxes accrued	-8,825	-379
Other current liabilities	3,204	1,673
Deferred charges and credits	-612	-1,537
Net cash provided by operating activities	26,452	31,312
Cash flows from investing activities:
Cash additions to utility property, plant and equipment	-73,865	-48,255
Cash additions to nuclear fuel	-10,183	-11,822
Capitalized interest and AFUDC:
Utility property, plant and equipment	-6,896	-4,590
Nuclear fuel	-1,289	-1,246
Allowance for equity funds used during construction	4,275	2,906
Decommissioning trust funds:
Purchases, including funding of $1.1 million	-26,961	-31,242
Sales and maturities	24,642	28,827
Proceeds from sale of property, plant and equipment	0	1,679
Other investing activities	-230	375
Net cash used for investing activities	-90,507	-63,368
Cash flows from financing activities:
Dividends paid	-11,303	-10,676
Borrowings under the revolving credit facility:
Proceeds	70,852	51,563
Payments	-27,039	-19,964
Other financing activities	-985	-1,067
Net cash provided by financing activities	31,525	19,856
Net decrease in cash and cash equivalents	-32,530	-12,200
Cash and cash equivalents at beginning of period	40,504	25,592
Cash and cash equivalents at end of period	$7,974	$13,392

Statements_Of_Cash_Flows_Paren

Statements Of Cash Flows Parenthetical (USD $)	3 Months Ended
In Millions, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014
Payments To Fund Decommissioning Fund	$1.10	$1.10

Principles_Of_Preparation

Principles Of Preparation	3 Months Ended
	Mar. 31, 2015
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, 2014 (the "2014 Form 10-K"). Capitalized terms used in this report and not defined herein have the meaning ascribed to such terms in the 2014 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, 2015 and December 31, 2014; the results of its operations and comprehensive operations for the three and twelve months ended March 31, 2015 and 2014; and its cash flows for the three months ended March 31, 2015 and 2014. The results of operations and comprehensive operations for the three months ended March 31, 2015 and the cash flows for the three months ended March 31, 2015 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, 2015 and $21.2 million at December 31, 2014. The Company presents revenues net of sales taxes in its statements of operations.
	Supplemental Cash Flow Disclosures (in thousands)
			Three Months Ended
			March 31,
			2015			2014
	Cash paid (received) for:
		Interest on long-term debt and borrowing under the revolving credit facility	$	10,117		$	10,174
		Income tax refunded, net	(807		)	(767		)
	Non-cash financing activities:
		Grants of restricted shares of common stock	523			1,197
	New Accounting Standards. In May 2014, the FASB issued new guidance (ASU 2014-09, Revenue from Contracts with Customers (Topic 606)) to provide a framework that replaces the existing revenue recognition guidance. ASU 2014-09 is the result of a joint effort by the FASB and the International Accounting Standards Board (IASB) intended to clarify the principles for recognizing revenue and to develop a common revenue standard for U.S. Generally Accepted Accounting Principles ("GAAP") and International Financial Reporting Standards. ASU 2014-09 provides that an entity should recognize the amount of revenue to which it expects to be entitled for the transfer of promised goods or services to customers. ASU 2014-09 is effective for annual periods and interim periods within that reporting period beginning after December 15, 2016, for public business entities. On April 1, 2015, the FASB voted to propose to defer the effective date to December 15, 2017. Early adoption of ASU 2014-09 is permitted after December 15, 2016. The Company is currently assessing the future impact of this ASU.
	In April 2015, the FASB issued new guidance (ASU 2015-03, Interest - Imputation of Interest (Topic 715)) to simplify the presentation of debt issuance costs. ASU 2015-03 requires that debt issuance costs related to a recognized debt liability be presented in the balance sheet as a direct deduction from the carrying amount of that debt liability, consistent with debt discounts. The recognition and measurement guidance for debt issuance costs are not affected by this ASU. ASU 2015-03 is effective for financial statements issued for fiscal years beginning after December 15, 2015, and interim periods within those fiscal years. The Company does not expect this ASU will materially impact the Company's results of operations and cash flows.

Accumulated_Other_Comprehensiv

Accumulated Other Comprehensive Income (Notes)	3 Months Ended
	Mar. 31, 2015
Accumulated Other Comprehensive Income (Loss) [Line Items]
Comprehensive Income (Loss) Note	Accumulated Other Comprehensive Income (Loss)
	Changes in Accumulated Other Comprehensive Income (Loss) (net of tax) by component are presented below (in thousands):
			Three Months Ended March 31, 2015																Three Months Ended March 31, 2014
			Unrecognized Pension and Post-retirement Benefit Costs				Net Unrealized Gains (Losses) on Marketable Securities				Net Losses on Cash Flow Hedges				Accumulated Other Comprehensive Income (Loss)				Unrecognized Pension and Post-retirement 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		$	(34,884	)		$	38,957			$	(12,074	)		$	(8,001	)		$	(21,330	)	$	36,240		$	(12,298	)	$	2,612
		Other comprehensive income before reclassifications	—				822				—				822				12,147			799			—			12,946
		Amounts reclassified from accumulated other comprehensive income (loss)	256				(2,997		)		42				(2,699		)		(205		)	(2,309		)	15			(2,499		)
	Balance at end of period		$	(34,628	)		$	36,782			$	(12,032	)		$	(9,878	)		$	(9,388	)	$	34,730		$	(12,283	)	$	13,059
			Twelve Months Ended March 31, 2015																Twelve Months Ended March 31, 2014
			Unrecognized Pension and Post-retirement Benefit Costs				Net Unrealized Gains (Losses) on Marketable Securities				Net Losses on Cash Flow Hedges				Accumulated Other Comprehensive Income (Loss)				Unrecognized Pension and Post-retirement 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		$	(9,388	)		$	34,730			$	(12,283	)		$	13,059			$	(75,032	)	$	27,858		$	(12,492	)	$	(59,666	)
		Other comprehensive income (loss) before reclassifications	(24,775		)		8,717				—				(16,058		)		63,599			9,738			—			73,337
		Amounts reclassified from accumulated other comprehensive income (loss)	(465		)		(6,665		)		251				(6,879		)		2,045			(2,866		)	209			(612		)
	Balance at end of period		$	(34,628	)		$	36,782			$	(12,032	)		$	(9,878	)		$	(9,388	)	$	34,730		$	(12,283	)	$	13,059
	Amounts reclassified from accumulated other comprehensive income (loss) for the three and twelve months ended March 31, 2015 and 2014 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
				2015				2014				2015				2014
	Amortization of pension and post-retirement benefit costs:
		Prior service benefit		$	1,663			1,459				$	7,863			$	5,619			(a)
		Net loss		(2,250		)		(1,123		)		(7,309		)		(8,920		)		(a)
				(587		)		336				554				(3,301		)		(a)
		Income tax effect		331				(131		)		(89		)		1,256
				(256		)		205				465				(2,045		)		(a)
	Marketable securities:
		Net realized gain on sale of securities		3,745				2,865				8,230				3,576				Investment and interest income, net
				3,745				2,865				8,230				3,576				Income before income taxes
		Income tax effect		(748		)		(556		)		(1,565		)		(710		)		Income tax expense
				2,997				2,309				6,665				2,866				Net income
	Loss on cash flow hedge:
		Amortization of loss		(114		)		(107		)		(445		)		(417		)		Interest on long-term debt and revolving credit facility
				(114		)		(107		)		(445		)		(417		)		Income before income taxes
		Income tax effect		72				92				194				208				Income tax expense
				(42		)		(15		)		(251		)		(209		)		Net income
		Total reclassifications		$	2,699			$	2,499			$	6,879			$	612
	(a) These items are included in the computation of net periodic benefit cost. See Note I, Employee Benefits, for additional information.

Regulation

Regulation	3 Months Ended
	Mar. 31, 2015
Public Utilities, General Disclosures [Abstract]
Regulation	Regulation
	General
	The rates and services of the Company are regulated by incorporated municipalities in Texas, the Public Utility Commission of Texas ("PUCT"), the New Mexico Public Regulation Commission ("NMPRC"), and the Federal Energy Regulatory Commission ("FERC"). Municipal orders, ordinances and other agreements regarding rates and services adopted by Texas municipalities are subject to review and approval by the PUCT. 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, the NMPRC and the FERC are subject to judicial review.
	Texas Regulatory Matters
	2012 Texas Retail Rate Case. 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 2012 Texas retail rate 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 discussed below. The 2012 Texas retail rate 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.
	Energy Efficiency Cost Recovery Factor. The Company made its annual filing to establish its energy efficiency cost recovery factor for 2015 on May 1, 2014. In addition to projected energy efficiency costs for 2015 and true-up to prior year actual costs, the Company requested approval of a $2.0 million bonus for the 2013 energy efficiency program results in accordance with PUCT rules. The PUCT approved the Company's request at its November 14, 2014 open meeting. The Company recorded the $2.0 million bonus as operating revenue in the fourth quarter of 2014.
	On May 1, 2015, the Company made its annual filing to establish its energy efficiency cost recovery factor for 2016. In addition to projected energy efficiency costs for 2016 and true-up to prior year actual costs, the Company requested approval of a $1.0 million bonus for the 2014 energy efficiency program results in accordance with PUCT rules. This case was assigned PUCT Docket No. 44677. No procedural schedule has yet been issued.
	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. The Texas Fuel Rule requires the Company to request to refund fuel costs in any month when the over-recovery balance exceeds a threshold material amount and it expects fuel costs to continue to be materially over-recovered. The Texas Fuel Rule also permits the Company to seek to surcharge fuel under-recoveries in any month the balance exceeds a threshold material amount and it expects fuel cost recovery to continue to be materially under-recovered. Fuel over and under-recoveries are considered material when they exceed 4% of the previous twelve months' fuel costs. All such fuel revenue and expense activities are subject to periodic final review by the PUCT in fuel reconciliation proceedings.
	On April 15, 2014, the Company filed a request, which was assigned PUCT Docket No. 42384, to increase its fixed fuel factor by approximately $10.7 million annually or 6.9%, pursuant to its approved formula. The revised fixed fuel factor reflected an expected increase in prices for natural gas over the twelve month period beginning March 2014. The increase in the fixed fuel factor received final approval on May 28, 2014 and was effective with May 2014 billings. As of March 31, 2015, the Company had slightly over-recovered fuel costs in the amount of $3.6 million for the Texas jurisdiction. On April 15, 2015, the Company filed a request, which was assigned PUCT Docket No. 44633, to reduce its fixed fuel factor by approximately 24% to reflect the reduction in fuel expense. The over-recovered balance is below the materiality threshold. On April 30, 2015, the Administrative Law Judge issued an order approving the proposed reduction on an interim basis effective May 1, 2015.
	Fuel Reconciliation Proceeding. Pursuant to the 2012 Texas retail rate settlement discussed above, on September 27, 2013, the Company filed an application with the PUCT, designated as PUCT 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. A settlement was reached and a final order was issued by the PUCT on July 11, 2014. The PUCT's final order completes the regulatory review and reconciliation of the Company's fuel expenses for the period through March 31, 2013.
	The settlement provides that 100% of margins on non-arbitrage off-system sales (as defined by the settlement) and 50% of margins on arbitrage off-system sales be shared with its Texas customers beginning April 1, 2014. For the period April 1, 2014 through June 30, 2015, the Company's total share of margins assignable to Texas retail jurisdiction, on arbitrage and non-arbitrage off-system sales, may not exceed 10% of the total margins assignable to the Texas retail jurisdiction on all off-system sales. The Company also agreed to file with the PUCT a proceeding to address the reasonableness of the Company's decision to not continue to participate in the Four Corners coal-fired generating Units 4 and 5 after July 2016. It is expected that issues related to the final coal mine closing and reclamation costs will be addressed in that proceeding as well as other issues related to post-participation events such as the asset retirement obligations of the Company related to those two units.
	Montana Power Station Approvals. The Company has received a Certificate of Convenience and Necessity ("CCN") from the PUCT to construct four natural gas fired generating units at the Montana Power Station ("the MPS") in El Paso County, Texas. The Company also obtained air permits from the Texas Commission on Environmental Quality ("TCEQ") and the U.S. Environmental Protection Agency ("EPA").
	The PUCT has issued final orders approving CCNs for the MPS to Caliente transmission line, MPS In & Out transmission line and the MPS to Montwood transmission line. These transmission lines will connect MPS to the Company’s transmission system for delivery of electricity throughout its service territory. MPS Units 1 and 2 and the MPS to Caliente and MPS In & Out transmission lines became operational in March 2015.
	Solar Generation CCN Filing. On April 20, 2015, the Company filed a petition with the PUCT requesting CCN authorization to construct a new 20 megawatt solar-powered generation facility to be located on Fort Bliss in the Company's service territory in Texas. The new facility will be a system resource. The Company has requested a PUCT final order by November 30, 2015 so that the project can be completed before December 31, 2016 to maximize potential tax benefits. This case was assigned PUCT Docket No. 44637. No procedural schedule has yet been issued.
	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 are updated annually for adjustment to the recovery factors.
	Fuel and Purchased Power Costs. Fuel and purchased power costs are recovered through base rates and a Fuel and Purchased Power Cost Adjustment Clause (the "FPPCAC") that accounts for changes in the costs of fuel included in base rates. On January 8, 2014, the NMPRC approved the continuation of the FPPCAC without modification in NMPRC Case No. 13-00380-UT. Fuel and purchased power costs are reconciled to actual costs on a monthly basis and recovered or refunded to customers the second succeeding month. The Company recovers costs related to Palo Verde Unit 3 capacity and energy in New Mexico through the FPPCAC as purchased power using a proxy market price approved in the 2014 FPPCAC continuation.
	Montana Power Station Approvals. The Company has received a CCN from the NMPRC to construct four units at the MPS and associated transmission lines. The Company also obtained all necessary air permits from the TCEQ and EPA. A final order in NMPRC Case No. 13-00297-UT approving the CCN for MPS Units 3 and 4 was issued on June 11, 2014. MPS Units 1 and 2 and the MPS to Caliente and MPS In & Out transmission lines became operational in March 2015.
	Solar Generation CCN Filing. On April 20, 2015, the Company filed a petition with the NMPRC requesting CCN authorization to construct a new 20 megawatt solar-powered generation facility to be located on Fort Bliss in the Company's service territory in Texas. The new facility will be a system resource. The Company has requested a NMPRC final order by November 30, 2015 so that the project can be completed before December 31, 2016 to maximize potential tax benefits. This case was assigned NMPRC Case No. 15-00099-UT. No procedural schedule has yet been issued.
	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") Transmission Rate Case. On December 31, 2012, PNM filed with FERC to change its method of transmission rate recovery for its transmission delivery services from stated rates to formula rates. The Company takes transmission service from PNM and is among the PNM transmission customers affected by PNM's shift to formula rates. On March 1, 2013, the FERC issued an order rejecting in part PNM's filing, and establishing settlement judge and hearing procedures. On March 20, 2015, PNM filed with FERC a settlement agreement and offer of settlement resolving all issues set for hearing in the proceeding. The Company cannot predict the outcome of the case at this time.
	Other Required Approvals. The Company has obtained required approvals for rates and tariffs, securities transactions and other approvals as required by the FERC.

Palo_Verde

Palo Verde	3 Months Ended
	Mar. 31, 2015
Palo Verde [Abstract]
Palo Verde	Palo Verde
	Spent Nuclear Fuel and Waste Disposal
	Pursuant to the Nuclear Waste Policy Act of 1982, as amended in 1987 (the "NWPA"), the DOE is legally obligated to accept and dispose of all spent nuclear fuel and other high-level radioactive waste generated by all domestic power reactors by 1998. The DOE's obligations are reflected in a contract for Disposal of Spent Nuclear Fuel and/or High-Level Radioactive Waste (the "Standard Contract") with each nuclear power plant. The DOE failed to begin accepting spent nuclear fuel by 1998. On December 19, 2012, Arizona Public Service Company ("APS"), acting on behalf of itself and the participant owners of Palo Verde, filed a second breach of contract lawsuit against the DOE. This lawsuit sought to recover damages incurred due to the DOE's failure to accept Palo Verde's spent nuclear fuel for the period beginning January 1, 2007 through June 30, 2011. On August 18, 2014, APS and the DOE entered into a settlement agreement, stipulating to a dismissal of the lawsuit and payment of $57.4 million by the DOE to the Palo Verde owners for certain specified costs incurred by Palo Verde during the period January 1, 2007 through June 30, 2011. On October 8, 2014, the Company received approximately $9.1 million, representing its share of the award. The majority of the award was credited to customers through the applicable fuel adjustment clauses. On October 31, 2014, APS acting on behalf of itself and the participant owners of Palo Verde, submitted to the government an additional request for reimbursement of spent nuclear fuel storage costs for the period July 1, 2011 through June 30, 2014. The accepted claim amount was $42.0 million. The Company’s share of the award is $6.6 million which is recorded as an accounts receivable as of March 31, 2015. The majority of the award was credited to customers through the applicable fuel adjustment clauses in March 2015. The reimbursement is anticipated to be received in the second quarter of 2015.

Common_Stock

Common Stock	3 Months Ended
	Mar. 31, 2015
Common Stock, Number of Shares, Par Value and Other Disclosures [Abstract]
Shareholders' Equity and Share-based Payments, Including Earnings Per Share Information	Common Stock
	Dividends. The Company paid $11.3 million and $10.7 million in quarterly cash dividends during the three months ended March 31, 2015 and 2014, respectively. The Company paid a total of $45.2 million and $42.7 million in quarterly cash dividends during the twelve months ended March 31, 2015 and 2014 , 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,
		2015				2014			2015			2014
	Weighted average number of common shares outstanding:
	Basic number of common shares outstanding	40,243,199				40,149,083			40,214,198			40,132,106
	Dilutive effect of unvested performance awards	23,475				—			26,595			12,053
	Diluted number of common shares outstanding	40,266,674				40,149,083			40,240,793			40,144,159
	Basic net income per common share:
	Net income	$	3,458			$	4,615		$	90,271		$	85,564
	Income allocated to participating restricted stock	(33		)		(36		)	(289		)	(260		)
	Net income available to common shareholders	$	3,425			$	4,579		$	89,982		$	85,304
	Diluted net income per common share:
	Net income	$	3,458			$	4,615		$	90,271		$	85,564
	Income reallocated to participating restricted stock	(33		)		(36		)	(289		)	(260		)
	Net income available to common shareholders	$	3,425			$	4,579		$	89,982		$	85,304
	Basic net income per common share:
	Distributed earnings	$	0.28			$	0.265		$	1.12		$	1.06
	Undistributed earnings	(0.19		)		(0.155		)	1.12			1.07
	Basic net income per common share	$	0.09			$	0.11		$	2.24		$	2.13
	Diluted net income per common share:
	Distributed earnings	$	0.28			$	0.265		$	1.12		$	1.06
	Undistributed earnings	(0.19		)		(0.155		)	1.12			1.06
	Diluted net income per common share	$	0.09			$	0.11		$	2.24		$	2.12
	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,
		2015			2014			2015		2014
	Restricted stock awards	68,195			79,413			57,651		57,017
	Performance shares (a)	59,898			128,508			42,506		90,384
	(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, 2015
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 2010. The Company is currently under audit in Texas for tax years 2007 through 2011 and in Arizona for tax years 2009 through 2012.
	For the three months ended March 31, 2015 and 2014, the Company’s effective tax rate was 22.2% and 24.2%, respectively. For the twelve months ended March 31, 2015 and 2014, the Company's effective tax rate was 31.0% and 32.8%, respectively. The Company's effective tax rate for the three months ended March 31, 2015 differs from the federal statutory tax rate of 35.0% primarily due due to capital gains in the decommissioning trusts realized in the first quarter of 2015, which are taxed at a federal rate of 20.0% and the allowance for equity funds used during construction (“AEFUDC”). The Company’s effective tax rate for the twelve months ended March 31, 2015 differs from the federal statutory tax rate of 35.0% primarily due to AEFUDC, capital gains in the decommissioning trust which are taxed at a federal tax rate of 20.0% and state income taxes.

Commitments_Contingencies_And_

Commitments, Contingencies And Uncertainties	3 Months Ended
	Mar. 31, 2015
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 2014 Annual Report on Form 10-K. In addition, see Notes C and D above and Notes C and E of Notes to Financial Statements in the 2014 Annual Report on 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 2014 Form 10-K.
	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 2014 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. Circuit") 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 reversed and upheld CSAPR, remanding certain portions of CSAPR to the D.C. Circuit for further consideration. On June 26, 2014, the EPA filed a motion asking the D.C. Circuit to lift its stay on CSAPR. On October 23, 2014, the D.C Circuit lifted its stay of CSAPR, and while we are unable to determine the full impact of the reinstatement of CSAPR until the D.C. Circuit and the EPA take further action, the Company believes it is currently positioned to comply with CSAPR.
	National Ambient Air Quality Standards. Under the CAA, the EPA sets National Ambient Air Quality Standards ("NAAQS") for six criteria pollutants considered harmful to public health and the environment, including PM, NOx, carbon monoxide ("CO"), ozone and SO2. NAAQS must be reviewed by the EPA at five-year intervals. In 2010, the EPA tightened the NAAQS for both NOx and SO2. The EPA is considering a 1-hour secondary NAAQS for NOx and SO2. In January 2013, the EPA tightened the NAAQS for fine PM. On November 26, 2014, the EPA announced a proposal to tighten the 2008 primary and secondary ground-level ozone NAAQS. Ozone is the main component of smog. While not directly emitted into the air, it forms from precursors, including NOx and volatile organic compounds, in combination with sunlight. EPA proposes to tighten the current 8-hour primary (health-based) standard of 75 parts per billion ("ppb") to a level within its preferred range of 65 to 70 ppb, while also taking comment on a potential standard as low as 60 ppb and on retaining the current standard. The EPA is expected to issue a final rule by November 2015 and make attainment/nonattainment designations for any revised standards by November 2017. The Company continues to evaluate what impact these final and proposed NAAQS could have on its operations. If the Company is required to install additional equipment to control emissions at its facilities, the revised NAAQS could have a material impact on its operations and financial results.
	Other Laws and Regulations and Risks. The Company has entered into an agreement to sell its interest in Four Corners Generating Station ("Four Corners") to APS at the expiration of the 50-year participation agreement in July 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. By ceasing its participation in Four Corners, the Company will avoid the significant cost required to install expensive pollution control equipment in order to continue operation of the plant as well as the risks of water availability that might adversely affect the amount of power available, or the price thereof, from Four Corners in the future. The closing of the transaction is subject to the receipt of regulatory approvals.
	In 2012, several environmental groups filed a lawsuit in federal district court against the Office of Surface Mining Reclamation and Enforcement (“OSM”) of the U.S. Department of the Interior challenging OSM’s 2012 approval of a permit revision which allowed for the expansion of mining operations into a new area of the mine that serves Four Corners (“Area IV North”). In April 2015, the court issued an order invalidating the permit revision, thereby prohibiting mining in Area IV North until OSM takes action to cure the defect in its permitting process identified by the court. Navajo Transitional Energy Company, the owner of the mine and supplier of coal to Four Corners, has indicated that it does not anticipate any near-term interruption of coal supply to the plant as a result of the suspension of mining in Area IV North. The Company cannot predict the time period that will be required for OSM’s further permitting process to be completed or whether the outcome of the process will be sufficient to allow the permit to be reinstated.
	Climate Change. The U.S. federal government has either considered, proposed and/or finalized legislation or regulations limiting GHG emissions, including carbon dioxide. In particular, the U.S. Congress has considered legislation to restrict or regulate GHG emissions. In the past few years, the EPA began using the CAA to regulate carbon dioxide and other GHG emissions, such as the 2009 GHG Reporting Rule and the EPA's sulfur hexafluoride ("SF6") reporting rule, both of which apply to the Company, as well as the EPA's 2010 actions to impose permitting requirements on new and modified sources of GHG emissions. After announcing his plan to address climate change in 2013, the President directed the EPA to issue proposals for GHG rulemaking addressing power plants. In January 2014, the EPA published a proposal to establish new source performance standards limiting carbon dioxide emissions from new electric generating units, and in June 2014, a proposal to create carbon dioxide standards for existing and modified/reconstructed power plants. The Company participated in the associated proposed rulemaking comment periods. On January 7, 2015, EPA announced it plans to issue final rules for new, existing and modified/reconstructed power plants by this summer. Given the very significant remaining uncertainties regarding these EPA 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 certain of 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 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 November 2014, 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 with certainty the final outcome of these settlement negotiations. The Company has accrued a total of $0.6 million as its estimated share of the loss contingency related to this matter.
	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. Settlement discussions are on-going. The Company does not expect the outcome of this matter to have a material impact on its financial position, results of operations or cash flows.
	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, 2015
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. The Company expenses legal costs, including expenses related to loss contingencies, as they are incurred.
	See Notes C and G above and Notes C and K of the Notes to Financial Statements in the 2014 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, 2015
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, 2015 and 2014 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,
		2015			2014			2015			2014
	Components of net periodic benefit cost:
	Service cost	$	2,100		$	2,173		$	8,514		$	9,100
	Interest cost	3,625			3,870			14,797			14,084
	Expected return on plan assets	(4,947		)	(4,680		)	(18,966		)	(17,513		)
	Amortization of:
	Net loss	2,750			1,773			9,830			10,196
	Prior service benefit	(888		)	(259		)	(3,535		)	(187		)
	Net periodic benefit cost	$	2,640		$	2,877		$	10,640		$	15,680
	During the three months ended March 31, 2015, the Company contributed $2.8 million of its projected $11.1 million 2015 annual contribution to its retirement plans.
	Other Postretirement Benefits
	The net periodic benefit cost recognized for the three and twelve months ended March 31, 2015 and 2014 is made up of the components listed below (in thousands):
		Three Months Ended						Twelve Months Ended
		March 31,						March 31,
		2015			2014			2015			2014
	Components of net periodic benefit cost:
	Service cost	$	875		$	700		$	3,020		$	3,443
	Interest cost	1,025			1,125			4,363			4,906
	Expected return on plan assets	(525		)	(525		)	(2,116		)	(2,001		)
	Amortization of:
	Prior service benefit	(775		)	(1,200		)	(4,328		)	(5,432		)
	Net gain	(500		)	(650		)	(2,521		)	(1,276		)
	Net periodic benefit cost (benefit)	$	100		$	(550	)	$	(1,582	)	$	(360	)
	The Company has not contributed to its other postretirement benefits plan during the three months ended March 31, 2015 and does not expect to contribute to its other postretirement benefit plan in 2015.

Financial_Instruments_And_Inve

Financial Instruments And Investments (Notes)	3 Months Ended
	Mar. 31, 2015
Fair Value Disclosures [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, 2015						December 31, 2014
		Carrying			Estimated			Carrying			Estimated
		Amount			Fair			Amount			Fair
					Value						Value
	Pollution Control Bonds	$	193,135		$	212,948		$	193,135		$	213,083
	Senior Notes	846,070			1,010,568			846,044			968,728
	RGRT Senior Notes (1)	110,000			118,070			110,000			117,215
	RCF (1)	58,345			58,345			14,532			14,532
	Total	$	1,207,550		$	1,399,931		$	1,163,711		$	1,313,558
	_______________
	-1	Nuclear fuel financing as of March 31, 2015 and December 31, 2014 is funded through the $110 million RGRT Senior Notes and $17.3 million and $14.5 million, respectively under the RCF. As of March 31, 2015, $41.0 million was outstanding under the RCF for working capital or general corporate purposes. As of December 31, 2014, 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 $237.6 million and $234.3 million at March 31, 2015 and December 31, 2014, 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, 2015
		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	$	—		$	—		$	2,362		$	(32	)	$	2,362	$	(32	)
	U.S. Government Bonds	—			—			17,868			(453		)	17,868		(453		)
	Municipal Obligations	9,265			(126		)	8,807			(465		)	18,072		(591		)
	Corporate Obligations	2,833			(66		)	2,508			(103		)	5,341		(169		)
	Total Debt Securities	12,098			(192		)	31,545			(1,053		)	43,643		(1,245		)
	Common Stock	3,414			(139		)	—			—			3,414		(139		)
	Total Temporarily Impaired Securities	$	15,512		$	(331	)	$	31,545		$	(1,053	)	$	47,057	$	(1,384	)
	_________________
	-1	Includes 108 securities.
		December 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 (2):
	Federal Agency Mortgage Backed Securities	$	—		$	—		$	2,383		$	(57	)	$	2,383	$	(57	)
	U.S. Government Bonds	1,552			(2		)	20,060			(573		)	21,612		(575		)
	Municipal Obligations	6,433			(65		)	8,570			(410		)	15,003		(475		)
	Corporate Obligations	2,455			(24		)	2,461			(111		)	4,916		(135		)
	Total Debt Securities	10,440			(91		)	33,474			(1,151		)	43,914		(1,242		)
	Common Stock	1,475			(229		)	—			—			1,475		(229		)
	Common Collective Trust-Equity Funds	22,736			(821		)	—			—			22,736		(821		)
	Total Temporarily Impaired Securities	$	34,651		$	(1,141	)	$	33,474		$	(1,151	)	$	68,125	$	(2,292	)
	_________________
	-2	Includes 106 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 is expected or is scheduled 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, 2015						December 31, 2014
		Fair			Unrealized			Fair			Unrealized
		Value			Gains			Value			Gains
	Description of Securities:
	Federal Agency Mortgage Backed Securities	$	18,270		$	770		$	15,388		$	665
	U.S. Government Bonds	24,984			630			20,016			567
	Municipal Obligations	11,594			543			11,642			595
	Corporate Obligations	15,662			1,038			13,762			850
	Total Debt Securities	70,510			2,981			60,808			2,677
	Common Stock	90,331			43,886			99,160			48,253
	Common Collective Trust-Equity Funds	23,760			745			—			—
	Cash and Cash Equivalents	5,961			—			6,193			—
	Total	$	190,562		$	47,612		$	166,161		$	50,930
	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 two years to six years and reflects anticipated future prepayments. The contractual year for maturity of these available-for-sale securities as of March 31, 2015 is as follows (in thousands):
		Total			2015			2016			2020 through 2024			2025 and Beyond
								through
								2019
	Municipal Debt Obligations	$	29,666		$	837		$	11,093		$	12,963		$	4,773
Corporate Debt Obligations	21,003			713			5,849			7,748			6,693
U.S. Government Bonds	42,852			3,051			17,549			14,638			7,614
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. The Company did not recognize other than temporary impairment losses on its available-for-sale securities in the three and twelve month periods ending March 31, 2015 and 2014, respectively.
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,
	2015			2014			2015			2014
Proceeds from sales or maturities of available-for-sale securities	$	24,642		$	28,827		$	104,126		$	74,067
Gross realized gains included in pre-tax income	$	3,782		$	3,014		$	8,626		$	3,961
Gross realized losses included in pre-tax income	(37		)	(149		)	(396		)	(385		)
Net gains in pre-tax income	$	3,745		$	2,865		$	8,230		$	3,576
Net unrealized holding gains included in accumulated other comprehensive income	$	1,014		$	998		$	10,843		$	11,904
Net gains reclassified out of accumulated other comprehensive income	(3,745		)	(2,865		)	(8,230		)	(3,576		)
Net gains (losses) in other comprehensive income	$	(2,731	)	$	(1,867	)	$	2,613		$	8,328
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 analysis. Financial assets utilizing Level 3 inputs are 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, 2015 and December 31, 2014, 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, 2015			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	$	1,625		$	—		$	—		$	1,625
Available for sale:
U.S. Government Bonds	$	42,852		$	42,852		$	—		$	—
Federal Agency Mortgage Backed Securities	20,632			—			20,632			—
Municipal Obligations	29,666			—			29,666			—
Corporate Obligations	21,003			—			21,003			—
Subtotal, Debt Securities	114,153			42,852			71,301			—
Common Stock	93,745			93,745			—			—
Common Collective Trust-Equity Funds	23,760			—			23,760			—
Cash and Cash Equivalents	5,961			5,961			—			—
Total available for sale	$	237,619		$	142,558		$	95,061		$	—
Description of Securities	Fair Value as of December 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	$	1,653		$	—		$	—		$	1,653
Available for sale:
U.S. Government Bonds	$	41,628		$	41,628		$	—		$	—
Federal Agency Mortgage Backed Securities	17,771			—			17,771			—
Municipal Obligations	26,645			—			26,645			—
Corporate Obligations	18,678			—			18,678			—
Subtotal, Debt Securities	104,722			41,628			63,094			—
Common Stock	100,635			100,635			—			—
Common Collective Trust-Equity Funds	22,736			—			22,736			—
Cash and Cash Equivalents	6,193			6,193			—			—
Total available for sale	$	234,286		$	148,456		$	85,830		$	—
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, 2015 and 2014. 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, 2015 and 2014.

Principles_Of_Preparation_Poli

Principles Of Preparation (Policy)	3 Months Ended
	Mar. 31, 2015
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, 2015 and $21.2 million at December 31, 2014. The Company presents revenues net of sales taxes in its statements of operations.
New Accounting Standards, Policy	New Accounting Standards. In May 2014, the FASB issued new guidance (ASU 2014-09, Revenue from Contracts with Customers (Topic 606)) to provide a framework that replaces the existing revenue recognition guidance. ASU 2014-09 is the result of a joint effort by the FASB and the International Accounting Standards Board (IASB) intended to clarify the principles for recognizing revenue and to develop a common revenue standard for U.S. Generally Accepted Accounting Principles ("GAAP") and International Financial Reporting Standards. ASU 2014-09 provides that an entity should recognize the amount of revenue to which it expects to be entitled for the transfer of promised goods or services to customers. ASU 2014-09 is effective for annual periods and interim periods within that reporting period beginning after December 15, 2016, for public business entities. On April 1, 2015, the FASB voted to propose to defer the effective date to December 15, 2017. Early adoption of ASU 2014-09 is permitted after December 15, 2016. The Company is currently assessing the future impact of this ASU.
	In April 2015, the FASB issued new guidance (ASU 2015-03, Interest - Imputation of Interest (Topic 715)) to simplify the presentation of debt issuance costs. ASU 2015-03 requires that debt issuance costs related to a recognized debt liability be presented in the balance sheet as a direct deduction from the carrying amount of that debt liability, consistent with debt discounts. The recognition and measurement guidance for debt issuance costs are not affected by this ASU. ASU 2015-03 is effective for financial statements issued for fiscal years beginning after December 15, 2015, and interim periods within those fiscal years. The Company does not expect this ASU will materially impact the Company's results of operations and cash flows.

Principles_Of_Preparation_Tabl

Principles Of Preparation (Tables)	3 Months Ended
	Mar. 31, 2015
Supplemental Cash Flow Information [Abstract]
Cash Flow, Supplemental Disclosures
	Supplemental Cash Flow Disclosures (in thousands)
			Three Months Ended
			March 31,
			2015			2014
	Cash paid (received) for:
		Interest on long-term debt and borrowing under the revolving credit facility	$	10,117		$	10,174
		Income tax refunded, net	(807		)	(767		)
	Non-cash financing activities:
		Grants of restricted shares of common stock	523			1,197

Accumulated_Other_Comprehensiv1

Accumulated Other Comprehensive Income (Tables)	3 Months Ended
	Mar. 31, 2015
Accumulated Other Comprehensive Income (Loss) [Line Items]
Schedule of Accumulated Other Comprehensive Income (Loss)
	Changes in Accumulated Other Comprehensive Income (Loss) (net of tax) by component are presented below (in thousands):
			Three Months Ended March 31, 2015																Three Months Ended March 31, 2014
			Unrecognized Pension and Post-retirement Benefit Costs				Net Unrealized Gains (Losses) on Marketable Securities				Net Losses on Cash Flow Hedges				Accumulated Other Comprehensive Income (Loss)				Unrecognized Pension and Post-retirement 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		$	(34,884	)		$	38,957			$	(12,074	)		$	(8,001	)		$	(21,330	)	$	36,240		$	(12,298	)	$	2,612
		Other comprehensive income before reclassifications	—				822				—				822				12,147			799			—			12,946
		Amounts reclassified from accumulated other comprehensive income (loss)	256				(2,997		)		42				(2,699		)		(205		)	(2,309		)	15			(2,499		)
	Balance at end of period		$	(34,628	)		$	36,782			$	(12,032	)		$	(9,878	)		$	(9,388	)	$	34,730		$	(12,283	)	$	13,059
			Twelve Months Ended March 31, 2015																Twelve Months Ended March 31, 2014
			Unrecognized Pension and Post-retirement Benefit Costs				Net Unrealized Gains (Losses) on Marketable Securities				Net Losses on Cash Flow Hedges				Accumulated Other Comprehensive Income (Loss)				Unrecognized Pension and Post-retirement 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		$	(9,388	)		$	34,730			$	(12,283	)		$	13,059			$	(75,032	)	$	27,858		$	(12,492	)	$	(59,666	)
		Other comprehensive income (loss) before reclassifications	(24,775		)		8,717				—				(16,058		)		63,599			9,738			—			73,337
		Amounts reclassified from accumulated other comprehensive income (loss)	(465		)		(6,665		)		251				(6,879		)		2,045			(2,866		)	209			(612		)
	Balance at end of period		$	(34,628	)		$	36,782			$	(12,032	)		$	(9,878	)		$	(9,388	)	$	34,730		$	(12,283	)	$	13,059
Reclassification out of Accumulated Other Comprehensive Income	Amounts reclassified from accumulated other comprehensive income (loss) for the three and twelve months ended March 31, 2015 and 2014 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
				2015				2014				2015				2014
	Amortization of pension and post-retirement benefit costs:
		Prior service benefit		$	1,663			1,459				$	7,863			$	5,619			(a)
		Net loss		(2,250		)		(1,123		)		(7,309		)		(8,920		)		(a)
				(587		)		336				554				(3,301		)		(a)
		Income tax effect		331				(131		)		(89		)		1,256
				(256		)		205				465				(2,045		)		(a)
	Marketable securities:
		Net realized gain on sale of securities		3,745				2,865				8,230				3,576				Investment and interest income, net
				3,745				2,865				8,230				3,576				Income before income taxes
		Income tax effect		(748		)		(556		)		(1,565		)		(710		)		Income tax expense
				2,997				2,309				6,665				2,866				Net income
	Loss on cash flow hedge:
		Amortization of loss		(114		)		(107		)		(445		)		(417		)		Interest on long-term debt and revolving credit facility
				(114		)		(107		)		(445		)		(417		)		Income before income taxes
		Income tax effect		72				92				194				208				Income tax expense
				(42		)		(15		)		(251		)		(209		)		Net income
		Total reclassifications		$	2,699			$	2,499			$	6,879			$	612
	(a) These items are included in the computation of net periodic benefit cost. See Note I, Employee Benefits, for additional information.

Common_Stock_Tables

Common Stock (Tables)	3 Months Ended
	Mar. 31, 2015
Common Stock, Number of Shares, Par Value and Other 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,
		2015				2014			2015			2014
	Weighted average number of common shares outstanding:
	Basic number of common shares outstanding	40,243,199				40,149,083			40,214,198			40,132,106
	Dilutive effect of unvested performance awards	23,475				—			26,595			12,053
	Diluted number of common shares outstanding	40,266,674				40,149,083			40,240,793			40,144,159
	Basic net income per common share:
	Net income	$	3,458			$	4,615		$	90,271		$	85,564
	Income allocated to participating restricted stock	(33		)		(36		)	(289		)	(260		)
	Net income available to common shareholders	$	3,425			$	4,579		$	89,982		$	85,304
	Diluted net income per common share:
	Net income	$	3,458			$	4,615		$	90,271		$	85,564
	Income reallocated to participating restricted stock	(33		)		(36		)	(289		)	(260		)
	Net income available to common shareholders	$	3,425			$	4,579		$	89,982		$	85,304
	Basic net income per common share:
	Distributed earnings	$	0.28			$	0.265		$	1.12		$	1.06
	Undistributed earnings	(0.19		)		(0.155		)	1.12			1.07
	Basic net income per common share	$	0.09			$	0.11		$	2.24		$	2.13
	Diluted net income per common share:
	Distributed earnings	$	0.28			$	0.265		$	1.12		$	1.06
	Undistributed earnings	(0.19		)		(0.155		)	1.12			1.06
	Diluted net income per common share	$	0.09			$	0.11		$	2.24		$	2.12
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,
		2015			2014			2015		2014
	Restricted stock awards	68,195			79,413			57,651		57,017
	Performance shares (a)	59,898			128,508			42,506		90,384
	(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, 2015
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, 2015 and 2014 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,
		2015			2014			2015			2014
	Components of net periodic benefit cost:
	Service cost	$	2,100		$	2,173		$	8,514		$	9,100
	Interest cost	3,625			3,870			14,797			14,084
	Expected return on plan assets	(4,947		)	(4,680		)	(18,966		)	(17,513		)
	Amortization of:
	Net loss	2,750			1,773			9,830			10,196
	Prior service benefit	(888		)	(259		)	(3,535		)	(187		)
	Net periodic benefit cost	$	2,640		$	2,877		$	10,640		$	15,680
Other Postretirement Benefit 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, 2015 and 2014 is made up of the components listed below (in thousands):
		Three Months Ended						Twelve Months Ended
		March 31,						March 31,
		2015			2014			2015			2014
	Components of net periodic benefit cost:
	Service cost	$	875		$	700		$	3,020		$	3,443
	Interest cost	1,025			1,125			4,363			4,906
	Expected return on plan assets	(525		)	(525		)	(2,116		)	(2,001		)
	Amortization of:
	Prior service benefit	(775		)	(1,200		)	(4,328		)	(5,432		)
	Net gain	(500		)	(650		)	(2,521		)	(1,276		)
	Net periodic benefit cost (benefit)	$	100		$	(550	)	$	(1,582	)	$	(360	)

Financial_Instruments_And_Inve1

Financial Instruments And Investments (Tables)	3 Months Ended
	Mar. 31, 2015
Fair Value Disclosures [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, 2015						December 31, 2014
		Carrying			Estimated			Carrying			Estimated
		Amount			Fair			Amount			Fair
					Value						Value
	Pollution Control Bonds	$	193,135		$	212,948		$	193,135		$	213,083
	Senior Notes	846,070			1,010,568			846,044			968,728
	RGRT Senior Notes (1)	110,000			118,070			110,000			117,215
	RCF (1)	58,345			58,345			14,532			14,532
	Total	$	1,207,550		$	1,399,931		$	1,163,711		$	1,313,558
	_______________
	-1	Nuclear fuel financing as of March 31, 2015 and December 31, 2014 is funded through the $110 million RGRT Senior Notes and $17.3 million and $14.5 million, respectively under the RCF. As of March 31, 2015, $41.0 million was outstanding under the RCF for working capital or general corporate purposes. As of December 31, 2014, 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, 2015
		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	$	—		$	—		$	2,362		$	(32	)	$	2,362	$	(32	)
	U.S. Government Bonds	—			—			17,868			(453		)	17,868		(453		)
	Municipal Obligations	9,265			(126		)	8,807			(465		)	18,072		(591		)
	Corporate Obligations	2,833			(66		)	2,508			(103		)	5,341		(169		)
	Total Debt Securities	12,098			(192		)	31,545			(1,053		)	43,643		(1,245		)
	Common Stock	3,414			(139		)	—			—			3,414		(139		)
	Total Temporarily Impaired Securities	$	15,512		$	(331	)	$	31,545		$	(1,053	)	$	47,057	$	(1,384	)
	_________________
	-1	Includes 108 securities.
		December 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 (2):
	Federal Agency Mortgage Backed Securities	$	—		$	—		$	2,383		$	(57	)	$	2,383	$	(57	)
	U.S. Government Bonds	1,552			(2		)	20,060			(573		)	21,612		(575		)
	Municipal Obligations	6,433			(65		)	8,570			(410		)	15,003		(475		)
	Corporate Obligations	2,455			(24		)	2,461			(111		)	4,916		(135		)
	Total Debt Securities	10,440			(91		)	33,474			(1,151		)	43,914		(1,242		)
	Common Stock	1,475			(229		)	—			—			1,475		(229		)
	Common Collective Trust-Equity Funds	22,736			(821		)	—			—			22,736		(821		)
	Total Temporarily Impaired Securities	$	34,651		$	(1,141	)	$	33,474		$	(1,151	)	$	68,125	$	(2,292	)
	_________________
	-2	Includes 106 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 is expected or is scheduled 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, 2015						December 31, 2014
		Fair			Unrealized			Fair			Unrealized
		Value			Gains			Value			Gains
	Description of Securities:
	Federal Agency Mortgage Backed Securities	$	18,270		$	770		$	15,388		$	665
	U.S. Government Bonds	24,984			630			20,016			567
	Municipal Obligations	11,594			543			11,642			595
	Corporate Obligations	15,662			1,038			13,762			850
	Total Debt Securities	70,510			2,981			60,808			2,677
	Common Stock	90,331			43,886			99,160			48,253
	Common Collective Trust-Equity Funds	23,760			745			—			—
	Cash and Cash Equivalents	5,961			—			6,193			—
	Total	$	190,562		$	47,612		$	166,161		$	50,930
Contractual Year For Maturity Of Available-For-Sale Securities	The contractual year for maturity of these available-for-sale securities as of March 31, 2015 is as follows (in thousands):
		Total			2015			2016			2020 through 2024			2025 and Beyond
								through
								2019
	Municipal Debt Obligations	$	29,666		$	837		$	11,093		$	12,963		$	4,773
	Corporate Debt Obligations	21,003			713			5,849			7,748			6,693
	U.S. Government Bonds	42,852			3,051			17,549			14,638			7,614
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,
		2015			2014			2015			2014
	Proceeds from sales or maturities of available-for-sale securities	$	24,642		$	28,827		$	104,126		$	74,067
	Gross realized gains included in pre-tax income	$	3,782		$	3,014		$	8,626		$	3,961
	Gross realized losses included in pre-tax income	(37		)	(149		)	(396		)	(385		)
	Net gains in pre-tax income	$	3,745		$	2,865		$	8,230		$	3,576
	Net unrealized holding gains included in accumulated other comprehensive income	$	1,014		$	998		$	10,843		$	11,904
	Net gains reclassified out of accumulated other comprehensive income	(3,745		)	(2,865		)	(8,230		)	(3,576		)
	Net gains (losses) in other comprehensive income	$	(2,731	)	$	(1,867	)	$	2,613		$	8,328
Fair Value, Measurement Inputs, Disclosure	The fair value of the Company's decommissioning trust funds and investment in debt securities, at March 31, 2015 and December 31, 2014, 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, 2015			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	$	1,625		$	—		$	—		$	1,625
	Available for sale:
	U.S. Government Bonds	$	42,852		$	42,852		$	—		$	—
	Federal Agency Mortgage Backed Securities	20,632			—			20,632			—
	Municipal Obligations	29,666			—			29,666			—
	Corporate Obligations	21,003			—			21,003			—
	Subtotal, Debt Securities	114,153			42,852			71,301			—
	Common Stock	93,745			93,745			—			—
	Common Collective Trust-Equity Funds	23,760			—			23,760			—
	Cash and Cash Equivalents	5,961			5,961			—			—
	Total available for sale	$	237,619		$	142,558		$	95,061		$	—
	Description of Securities	Fair Value as of December 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	$	1,653		$	—		$	—		$	1,653
	Available for sale:
	U.S. Government Bonds	$	41,628		$	41,628		$	—		$	—
	Federal Agency Mortgage Backed Securities	17,771			—			17,771			—
	Municipal Obligations	26,645			—			26,645			—
	Corporate Obligations	18,678			—			18,678			—
	Subtotal, Debt Securities	104,722			41,628			63,094			—
	Common Stock	100,635			100,635			—			—
	Common Collective Trust-Equity Funds	22,736			—			22,736			—
	Cash and Cash Equivalents	6,193			6,193			—			—
	Total available for sale	$	234,286		$	148,456		$	85,830		$	—

Principles_Of_Preparation_Accr

Principles Of Preparation (Accrued Unbilled Revenues) (Details) (USD $)	Mar. 31, 2015	Dec. 31, 2014
In Millions, unless otherwise specified
Accounting Policies [Abstract]
Accrued unbilled revenues	$17.70	$21.20

Principles_Of_Preparation_Supp

Principles Of Preparation (Supplemental Cash Flow Disclosures) (Details) (USD $)	3 Months Ended
In Thousands, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014
Supplemental Cash Flow Information [Abstract]
Interest on long-term debt and borrowing under the revolving credit facility	$10,117	$10,174
Income tax refunded, net	-807	-767
Restricted Stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common stock issued	$523	$1,197

Accumulated_Other_Comprehensiv2

Accumulated Other Comprehensive Income by Component (Details) (USD $)	3 Months Ended		12 Months Ended
In Thousands, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014	Mar. 31, 2015	Mar. 31, 2014
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Accumulated Other Comprehensive Income (Loss), beginning balance	($8,001)	$2,612	$13,059	($59,666)
Other Comprehensive Income (Loss) before Reclassifications	822	12,946	-16,058	73,337
Amounts Reclassified from Accumulated Other Comprehensive Income (Loss)	-2,699	-2,499	-6,879	-612
Accumulated Other Comprehensive Income (Loss), ending balance	-9,878	13,059	-9,878	13,059
Accumulated Defined Benefit Plans Adjustment
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Accumulated Other Comprehensive Income (Loss), beginning balance	-34,884	-21,330	-9,388	-75,032
Other Comprehensive Income (Loss) before Reclassifications	0	12,147	-24,775	63,599
Amounts Reclassified from Accumulated Other Comprehensive Income (Loss)	256	-205	-465	2,045
Accumulated Other Comprehensive Income (Loss), ending balance	-34,628	-9,388	-34,628	-9,388
Accumulated Net Unrealized Investment Gain (Loss)
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Accumulated Other Comprehensive Income (Loss), beginning balance	38,957	36,240	34,730	27,858
Other Comprehensive Income (Loss) before Reclassifications	822	799	8,717	9,738
Amounts Reclassified from Accumulated Other Comprehensive Income (Loss)	-2,997	-2,309	-6,665	-2,866
Accumulated Other Comprehensive Income (Loss), ending balance	36,782	34,730	36,782	34,730
Accumulated Net Gain (Loss) from Designated or Qualifying Cash Flow Hedges
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Accumulated Other Comprehensive Income (Loss), beginning balance	-12,074	-12,298	-12,283	-12,492
Other Comprehensive Income (Loss) before Reclassifications	0	0	0	0
Amounts Reclassified from Accumulated Other Comprehensive Income (Loss)	42	15	251	209
Accumulated Other Comprehensive Income (Loss), ending balance	($12,032)	($12,283)	($12,032)	($12,283)

Accumulated_Other_Comprehensiv3

Accumulated Other Comprehensive Income Amounts Reclassified (Details) (USD $)	3 Months Ended				12 Months Ended
In Thousands, unless otherwise specified	Mar. 31, 2015		Mar. 31, 2014		Mar. 31, 2015		Mar. 31, 2014
Accumulated Other Comprehensive Income (Loss) [Line Items]
Prior service benefit	$1,663		$1,459		$7,863		$5,619
Interest on long-term debt and revolving credit facility	-12,736		-11,822		-47,732		-47,714
Income tax expense	984		1,473		40,599		41,813
Net income (loss)	3,425		4,579		89,982		85,304
Reclassification out of Accumulated Other Comprehensive Income
Accumulated Other Comprehensive Income (Loss) [Line Items]
Net income (loss)	2,699		2,499		6,879		612
Reclassification out of Accumulated Other Comprehensive Income | Accumulated Defined Benefit Plans Adjustment
Accumulated Other Comprehensive Income (Loss) [Line Items]
Prior service benefit	1,663	[1]	1,459	[1]	7,863	[1]	5,619	[1]
Net Loss	-2,250	[1]	-1,123	[1]	-7,309	[1]	-8,920	[1]
Income (Loss) before income tax	-587	[1]	336	[1]	554	[1]	-3,301	[1]
Income tax expense	331		-131		-89		1,256
Net income (loss)	-256	[1]	205	[1]	465	[1]	-2,045	[1]
Reclassification out of Accumulated Other Comprehensive Income | Accumulated Net Unrealized Investment Gain (Loss)
Accumulated Other Comprehensive Income (Loss) [Line Items]
Net Realized Gain on Sale of Securities	3,745		2,865		8,230		3,576
Income (Loss) before income tax	3,745		2,865		8,230		3,576
Income tax expense	-748		-556		-1,565		-710
Net income (loss)	2,997		2,309		6,665		2,866
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	-114		-107		-445		-417
Income (Loss) before income tax	-114		-107		-445		-417
Income tax expense	72		92		194		208
Net income (loss)	($42)		($15)		($251)		($209)
[1]	These items are included in the computation of net periodic benefit cost. See Note I, Employee Benefits, for additional information.

Regulation_Narrative_Details

Regulation (Narrative) (Details) (USD $)	12 Months Ended	0 Months Ended			3 Months Ended		0 Months Ended
	Feb. 28, 2015	Jul. 11, 2014	28-May-14	1-May-14	Dec. 31, 2014	Mar. 31, 2015	Apr. 15, 2015	1-May-15
Over-collection of fuel revenues					$932,000	6,366,000
PUCT Docket No. 42384
Period Of Expected Increases In Prices For Natural Gas	12 months
PUCT Docket No. 41852
Reconcilable Fuel Expense		545,300,000
Fuel Reconciliation Period		45 months
Retained Percentage Of Off System Sales Margins, Period Covered Start Date		1-Apr-14
Retained Percentage Of Off System Sales Margins, Period Covered End Date		30-Jun-15
Fixed Fuel Factor | PUCT Docket No. 42384
Increase (Decrease) In Fixed Fuel Factor			10,700,000
Percent Increase (Decrease) In Fixed Fuel Factor			6.90%
Non-Arbitrage Sales | PUCT Docket No. 41852
Customers' Percentage of Off System Sales Margins		100.00%
PUCT
Public Utilities Requested Performance Incentive Bonus Related To Energy Efficiency Program				2,000,000	2,000,000
Fuel Over And Under Materiality Threshold Percentage						4.00%
Over-collection of fuel revenues						3,600,000
Arbitrage Sales | PUCT Docket No. 41852
Customers' Percentage of Off System Sales Margins		50.00%
Four Corners Generating Station
Date participation is ceased						6-Jul-16
Number Of Power Generation Units						2
Montana Power Station | PUCT
Number of power generation units authorized to be constructed						4
Montana Power Station | NMPRC
Number of power generation units authorized to be constructed						4
Fort Bliss | PUCT
Electric Capacity						20
Fort Bliss | NMPRC
Electric Capacity						20
Minimum
Fixed Fuel Factor Revision Period, in Months						4 months
Maximum | PUCT Docket No. 41852
Retained Percentage of Off System Sales Margins		10.00%
Four Corners Generating Station
Date participation is ceased						6-Jul-16
Subsequent Event | Fixed Fuel Factor | PUCT Docket No. 44633
Public Utilities, Requested Rate Decrease, Percentage							24.00%
Subsequent Event | PUCT
Public Utilities Requested Performance Incentive Bonus Related To Energy Efficiency Program								$1,000,000

Palo_Verde_Narrative_Details

Palo Verde (Narrative) (Details) (USD $)	0 Months Ended				3 Months Ended
In Millions, unless otherwise specified	Aug. 18, 2014	Oct. 31, 2014	Dec. 19, 2012	Oct. 08, 2014	Jun. 30, 2015	Mar. 31, 2015
Jointly Owned Utility Plant Interests [Line Items]
Settlement Agreement, Date	18-Aug-14
Suit Against Department of Energy for Spent Fuel
Jointly Owned Utility Plant Interests [Line Items]
Settlement Agreement, Counterparty's Name			United States Department of Energy
Lawsuit Filing Date		31-Oct-14	19-Dec-12
Suit Against Department of Energy for Spent Fuel | Palo Verde Generating Station
Jointly Owned Utility Plant Interests [Line Items]
Settlement, Amount				$9.10
Settlement Agreement Award Received, Date				8-Oct-14
Settlement, Receivable						6.6
Suit Against Department of Energy for Spent Fuel | Palo Verde Participants
Jointly Owned Utility Plant Interests [Line Items]
Settlement, Amount	57.4	42
Minimum | Suit Against Department of Energy for Spent Fuel
Jointly Owned Utility Plant Interests [Line Items]
Litigation, Period Covered		1-Jul-11	1-Jan-07
Minimum | Scenario, Forecast | Suit Against Department of Energy for Spent Fuel
Jointly Owned Utility Plant Interests [Line Items]
Reimbursement anticipated to be received, date					1-Apr-15
Maximum | Suit Against Department of Energy for Spent Fuel
Jointly Owned Utility Plant Interests [Line Items]
Litigation, Period Covered		30-Jun-14	30-Jun-11
Maximum | Scenario, Forecast | Suit Against Department of Energy for Spent Fuel
Jointly Owned Utility Plant Interests [Line Items]
Reimbursement anticipated to be received, date					30-Jun-15

Common_Stock_Narrative_Details

Common Stock (Narrative) (Details) (USD $)	3 Months Ended		12 Months Ended
In Millions, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014	Mar. 31, 2015	Mar. 31, 2014
Dividends, Common Stock, Cash	$11.30	$10.70	$45.20	$42.70

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, 2015	Mar. 31, 2014	Mar. 31, 2015	Mar. 31, 2014
Earnings Per Share [Abstract]
Basic number of common shares outstanding	40,243,199	40,149,083	40,214,198	40,132,106
Dilutive effect of unvested performance awards	23,475	0	26,595	12,053
Diluted number of common shares outstanding	40,266,674	40,149,083	40,240,793	40,144,159
Net income	$3,458	$4,615	$90,271	$85,564
Income allocated to participating restricted stock	-33	-36	-289	-260
Net income available to common shareholders, basic	3,425	4,579	89,982	85,304
Income reallocated to participating restricted stock	-33	-36	-289	-260
Net income available to common shareholders, diluted	$3,425	$4,579	$89,982	$85,304
Earnings Per Share, Basic, Distributed	$0.28	$0.27	$1.12	$1.06
Earnings Per Share, Basic, Undistributed	($0.19)	($0.16)	$1.12	$1.07
Basic net income per common share	$0.09	$0.11	$2.24	$2.13
Earnings Per Share, Diluted, Distributed	$0.28	$0.27	$1.12	$1.06
Earnings Per Sare, Diluted, Undistributed	($0.19)	($0.16)	$1.12	$1.06
Diluted net income per common share	$0.09	$0.11	$2.24	$2.12

Common_Stock_Antidilutive_Secu

Common Stock (Antidilutive Securities Excluded From Computation Of Earnings Per Share) (Details)	3 Months Ended				12 Months Ended
	Mar. 31, 2015		Mar. 31, 2014		Mar. 31, 2015		Mar. 31, 2014
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	68,195		79,413		57,651		57,017
Performance Shares
Antidilutive Securities Excluded from the Computation of Diluted Earnings Per Share, Amount	59,898	[1]	128,508	[1]	42,506	[1]	90,384	[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_Income_Tax_Rates_

Income Taxes (Income Tax Rates) (Details)	3 Months Ended		12 Months Ended
	Mar. 31, 2015	Mar. 31, 2014	Mar. 31, 2015	Mar. 31, 2014
Income Tax [Line Items]
Consolidated effective tax rate	22.20%	24.20%	31.00%	32.80%
Federal statutory tax rate	35.00%		35.00%
Income Tax Rate Capital Gains	20.00%		20.00%

Income_Taxes_Details

Income Taxes (Details)	3 Months Ended
	Mar. 31, 2015
Internal Revenue Service (IRS) | Maximum
Income Tax [Line Items]
Tax Year Closed	2009
ARIZONA | Earliest Tax Year
Income Tax [Line Items]
Income Tax Examination, Year under Examination	2009
ARIZONA | Latest Tax Year
Income Tax [Line Items]
Income Tax Examination, Year under Examination	2012
NEW MEXICO | Maximum
Income Tax [Line Items]
Tax Year Closed	2009
TEXAS | Earliest Tax Year
Income Tax [Line Items]
Income Tax Examination, Year under Examination	2007
TEXAS | Latest Tax Year
Income Tax [Line Items]
Income Tax Examination, Year under Examination	2011

Commitments_Contingencies_And_1

Commitments, Contingencies And Uncertainties (Narrative) (Details) (USD $)	3 Months Ended
In Millions, unless otherwise specified	Mar. 31, 2015	Nov. 26, 2014
	Decimals	Decimals
Loss Contingencies [Line Items]
Number of criteria emissions established under the Clear Air Act	6
Frequency of Review by Environmental Protection Agency	5 years
Public Utilities, Government Standard Emission Limit	75
Accrual for Environmental Loss Contingencies	$0.60
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]
Public Utilities, Assessed Coal Severance Surtax Penalty and Interest	$1.50
Four Corners Generating Station
Loss Contingencies [Line Items]
Date participation is ceased	6-Jul-16
Minimum
Loss Contingencies [Line Items]
Public Utilities, Government Standard Emission Limit	65	60
Maximum
Loss Contingencies [Line Items]
Public Utilities, Government Standard Emission Limit	70

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, 2015	Mar. 31, 2014	Mar. 31, 2015	Mar. 31, 2014
Retirement Plans
Defined Benefit Plan Disclosure [Line Items]
Service cost	$2,100	$2,173	$8,514	$9,100
Interest cost	3,625	3,870	14,797	14,084
Expected return on plan assets	-4,947	-4,680	-18,966	-17,513
Amortization of prior service benefit	-888	-259	-3,535	-187
Amortization of net (gain) loss	2,750	1,773	9,830	10,196
Net periodic benefit cost (benefit)	2,640	2,877	10,640	15,680
Other Postretirement Benefit Plans
Defined Benefit Plan Disclosure [Line Items]
Service cost	875	700	3,020	3,443
Interest cost	1,025	1,125	4,363	4,906
Expected return on plan assets	-525	-525	-2,116	-2,001
Amortization of prior service benefit	-775	-1,200	-4,328	-5,432
Amortization of net (gain) loss	-500	-650	-2,521	-1,276
Net periodic benefit cost (benefit)	$100	($550)	($1,582)	($360)

Employee_Benefits_Narrative_De

Employee Benefits (Narrative) (Details) (Retirement Plans, USD $)	3 Months Ended
In Millions, unless otherwise specified	Mar. 31, 2015
Retirement Plans
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Employer Contribution	$2.80
Defined Benefit Plan, Expected Contributions in Current Fiscal Year	$11.10

Financial_Instruments_And_Inve2

Financial Instruments And Investments (Carrying Amount and Fair Value Amounts) (Details) (USD $)	Mar. 31, 2015		Dec. 31, 2014
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	$1,207,550		$1,163,711
Carrying (Reported) Amount, Fair Value Disclosure | Pollution Control Bonds
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Debt Instrument, Fair Value Disclosure	193,135		193,135
Carrying (Reported) Amount, Fair Value Disclosure | Senior Notes
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Debt Instrument, Fair Value Disclosure	846,070		846,044
Carrying (Reported) Amount, Fair Value Disclosure | RGRT Senior Notes
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Debt Instrument, Fair Value Disclosure	110,000	[1]	110,000	[1]
Carrying (Reported) Amount, Fair Value Disclosure | Revolving Credit Facility
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Debt Instrument, Fair Value Disclosure	58,345	[1]	14,532	[1]
Estimate of Fair Value Measurement
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Debt Instrument, Fair Value Disclosure	1,399,931		1,313,558
Estimate of Fair Value Measurement | Pollution Control Bonds
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Debt Instrument, Fair Value Disclosure	212,948		213,083
Estimate of Fair Value Measurement | Senior Notes
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Debt Instrument, Fair Value Disclosure	1,010,568		968,728
Estimate of Fair Value Measurement | RGRT Senior Notes
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Debt Instrument, Fair Value Disclosure	118,070	[1]	117,215	[1]
Estimate of Fair Value Measurement | Revolving Credit Facility
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Debt Instrument, Fair Value Disclosure	$58,345	[1]	$14,532	[1]
[1]	Nuclear fuel financing as of MarchB 31, 2015 and DecemberB 31, 2014 is funded through the $110 million RGRT Senior Notes and $17.3 million and $14.5 million, respectively under the RCF. As of MarchB 31, 2015, $41.0 million was outstanding under the RCF for working capital or general corporate purposes. As of DecemberB 31, 2014, 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.

Financial_Instruments_And_Inve3

Financial Instruments And Investments (Long-Term Debt and Short-Term Borrowings - Narratives) (Details) (USD $)	Mar. 31, 2015	Dec. 31, 2014	Aug. 18, 2010
In Thousands, unless otherwise specified
Financial Instruments and Investments [Line Items]
Decommissioning Fund Investments	$237,619	$234,286
Nuclear Fuel Financing
Financial Instruments and Investments [Line Items]
Line of Credit Facility, Amount Outstanding	17,300	14,500
Working Capital and General Purpose
Financial Instruments and Investments [Line Items]
Line of Credit Facility, Amount Outstanding	41,000	0
RGRT Senior Notes
Financial Instruments and Investments [Line Items]
Debt Instrument, Face Amount			$110,000

Financial_Instruments_And_Inve4

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, 2015		Dec. 31, 2014
	securities		securities
Financial Instruments and Investments [Line Items]
Marketable Securities Fair Value Less than 12 Months	$15,512	[1]	$34,651	[2]
Marketable Securities Unrealized Losses Less Than 12 Months	-331	[1]	-1,141	[2]
Marketable Securities Fair Value 12 Months or Longer	31,545	[1]	33,474	[2]
Marketable Securities Unrealized Losses 12 Months or Longer	-1,053	[1]	-1,151	[2]
Marketable Securities Fair Value Total	47,057	[1]	68,125	[2]
Marketable Securities Unrealized Losses Total	-1,384	[1]	-2,292	[2]
Number of securities	108		106
Debt Securities
Financial Instruments and Investments [Line Items]
Marketable Securities Fair Value Less than 12 Months	12,098	[1]	10,440	[2]
Marketable Securities Unrealized Losses Less Than 12 Months	-192	[1]	-91	[2]
Marketable Securities Fair Value 12 Months or Longer	31,545	[1]	33,474	[2]
Marketable Securities Unrealized Losses 12 Months or Longer	-1,053	[1]	-1,151	[2]
Marketable Securities Fair Value Total	43,643	[1]	43,914	[2]
Marketable Securities Unrealized Losses Total	-1,245	[1]	-1,242	[2]
Collateralized Mortgage Backed Securities
Financial Instruments and Investments [Line Items]
Marketable Securities Fair Value Less than 12 Months	0	[1]	0	[2]
Marketable Securities Unrealized Losses Less Than 12 Months	0	[1]	0	[2]
Marketable Securities Fair Value 12 Months or Longer	2,362	[1]	2,383	[2]
Marketable Securities Unrealized Losses 12 Months or Longer	-32	[1]	-57	[2]
Marketable Securities Fair Value Total	2,362	[1]	2,383	[2]
Marketable Securities Unrealized Losses Total	-32	[1]	-57	[2]
U.S. Government Bonds
Financial Instruments and Investments [Line Items]
Marketable Securities Fair Value Less than 12 Months	0	[1]	1,552	[2]
Marketable Securities Unrealized Losses Less Than 12 Months	0	[1]	-2	[2]
Marketable Securities Fair Value 12 Months or Longer	17,868	[1]	20,060	[2]
Marketable Securities Unrealized Losses 12 Months or Longer	-453	[1]	-573	[2]
Marketable Securities Fair Value Total	17,868	[1]	21,612	[2]
Marketable Securities Unrealized Losses Total	-453	[1]	-575	[2]
Municipal Bonds
Financial Instruments and Investments [Line Items]
Marketable Securities Fair Value Less than 12 Months	9,265	[1]	6,433	[2]
Marketable Securities Unrealized Losses Less Than 12 Months	-126	[1]	-65	[2]
Marketable Securities Fair Value 12 Months or Longer	8,807	[1]	8,570	[2]
Marketable Securities Unrealized Losses 12 Months or Longer	-465	[1]	-410	[2]
Marketable Securities Fair Value Total	18,072	[1]	15,003	[2]
Marketable Securities Unrealized Losses Total	-591	[1]	-475	[2]
Corporate Debt Securities
Financial Instruments and Investments [Line Items]
Marketable Securities Fair Value Less than 12 Months	2,833	[1]	2,455	[2]
Marketable Securities Unrealized Losses Less Than 12 Months	-66	[1]	-24	[2]
Marketable Securities Fair Value 12 Months or Longer	2,508	[1]	2,461	[2]
Marketable Securities Unrealized Losses 12 Months or Longer	-103	[1]	-111	[2]
Marketable Securities Fair Value Total	5,341	[1]	4,916	[2]
Marketable Securities Unrealized Losses Total	-169	[1]	-135	[2]
Equity Securities
Financial Instruments and Investments [Line Items]
Marketable Securities Fair Value Less than 12 Months	3,414	[1]	1,475	[2]
Marketable Securities Unrealized Losses Less Than 12 Months	-139	[1]	-229	[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	3,414	[1]	1,475	[2]
Marketable Securities Unrealized Losses Total	-139	[1]	-229	[2]
Common Collective Trust - Equity Funds
Financial Instruments and Investments [Line Items]
Marketable Securities Fair Value Less than 12 Months			22,736	[2]
Marketable Securities Unrealized Losses Less Than 12 Months			-821	[2]
Marketable Securities Fair Value 12 Months or Longer			0	[2]
Marketable Securities Unrealized Losses 12 Months or Longer			0	[2]
Marketable Securities Fair Value Total			22,736	[2]
Marketable Securities Unrealized Losses Total			($821)	[2]
[1]	Includes 108 securities.
[2]	Includes 106 securities.

Financial_Instruments_And_Inve5

Financial Instruments And Investments (Unrecognized Gross Unrealized Gains And The Fair Value) (Details) (USD $)	Mar. 31, 2015	Dec. 31, 2014
In Thousands, unless otherwise specified
Financial Instruments and Investments [Line Items]
Available-for-sale Securities, Unrealized Gain Position, Fair Value	$190,562	$166,161
Available-for-sale Securities, Gross Unrealized Gain	47,612	50,930
Debt Securities
Financial Instruments and Investments [Line Items]
Available-for-sale Securities, Unrealized Gain Position, Fair Value	70,510	60,808
Available-for-sale Securities, Gross Unrealized Gain	2,981	2,677
Collateralized Mortgage Backed Securities
Financial Instruments and Investments [Line Items]
Available-for-sale Securities, Unrealized Gain Position, Fair Value	18,270	15,388
Available-for-sale Securities, Gross Unrealized Gain	770	665
U.S. Government Bonds
Financial Instruments and Investments [Line Items]
Available-for-sale Securities, Unrealized Gain Position, Fair Value	24,984	20,016
Available-for-sale Securities, Gross Unrealized Gain	630	567
Municipal Bonds
Financial Instruments and Investments [Line Items]
Available-for-sale Securities, Unrealized Gain Position, Fair Value	11,594	11,642
Available-for-sale Securities, Gross Unrealized Gain	543	595
Corporate Debt Securities
Financial Instruments and Investments [Line Items]
Available-for-sale Securities, Unrealized Gain Position, Fair Value	15,662	13,762
Available-for-sale Securities, Gross Unrealized Gain	1,038	850
Equity Securities
Financial Instruments and Investments [Line Items]
Available-for-sale Securities, Unrealized Gain Position, Fair Value	90,331	99,160
Available-for-sale Securities, Gross Unrealized Gain	43,886	48,253
Common Collective Trust - Equity Funds
Financial Instruments and Investments [Line Items]
Available-for-sale Securities, Unrealized Gain Position, Fair Value	23,760	0
Available-for-sale Securities, Gross Unrealized Gain	745	0
Cash and Cash Equivalents
Financial Instruments and Investments [Line Items]
Available-for-sale Securities, Unrealized Gain Position, Fair Value	5,961	6,193
Available-for-sale Securities, Gross Unrealized Gain	$0	$0

Financial_Instruments_And_Inve6

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, 2015
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	29,666
2015	837
2016 through 2019	11,093
2020 through 2024	12,963
2025 and Beyond	4,773
Corporate Debt Obligations
Schedule of Available-for-sale Securities [Line Items]
Total	21,003
2015	713
2016 through 2019	5,849
2020 through 2024	7,748
2025 and Beyond	6,693
U.S. Government Bonds
Schedule of Available-for-sale Securities [Line Items]
Total	42,852
2015	3,051
2016 through 2019	17,549
2020 through 2024	14,638
2025 and Beyond	7,614
Minimum
Schedule of Available-for-sale Securities [Line Items]
Debt Instrument, Expected Weighted Average Maturity Year	2 years
Maximum
Schedule of Available-for-sale Securities [Line Items]
Debt Instrument, Expected Weighted Average Maturity Year	6 years

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, 2015	Mar. 31, 2014	Mar. 31, 2015	Mar. 31, 2014
Investment [Line Items]
Proceeds from sales of available-for-sale securities	$24,642	$28,827	$104,126	$74,067
Gross realized gains included in pre-tax income	3,782	3,014	8,626	3,961
Gross realized losses included in pre-tax income	-37	-149	-396	-385
Net unrealized holding gains (losses) included in accumulated other comprehensive income	1,014	998	10,843	11,904
Net gains (losses) in pre-tax income	3,745	2,865	8,230	3,576
Net gains (losses) in other comprehensive income	($2,731)	($1,867)	$2,613	$8,328

Financial_Instruments_And_Inve8

Financial Instruments And Investments (Company's Decommissioning Trust Funds And Investments In Debt Securities) (Details) (USD $)	Mar. 31, 2015	Dec. 31, 2014
In Thousands, unless otherwise specified
Decommisioning Fund Investments
Financial Instruments and Investments [Line Items]
Available-for-sale Securities	$237,619	$234,286
Decommisioning Fund Investments | Quoted Prices In Active Markets For Identical Assets (Level 1)
Financial Instruments and Investments [Line Items]
Available-for-sale Securities	142,558	148,456
Decommisioning Fund Investments | Significant Other Observable Inputs (Level 2)
Financial Instruments and Investments [Line Items]
Available-for-sale Securities	95,061	85,830
Decommisioning 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	1,625	1,653
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	1,625	1,653
Debt Securities | Decommisioning Fund Investments
Financial Instruments and Investments [Line Items]
Available-for-sale Securities	114,153	104,722
Debt Securities | Decommisioning Fund Investments | Quoted Prices In Active Markets For Identical Assets (Level 1)
Financial Instruments and Investments [Line Items]
Available-for-sale Securities	42,852	41,628
Debt Securities | Decommisioning Fund Investments | Significant Other Observable Inputs (Level 2)
Financial Instruments and Investments [Line Items]
Available-for-sale Securities	71,301	63,094
Debt Securities | Decommisioning Fund Investments | Significant Unobservable Inputs (Level 3)
Financial Instruments and Investments [Line Items]
Available-for-sale Securities	0	0
U.S. Government Bonds | Decommisioning Fund Investments
Financial Instruments and Investments [Line Items]
Available-for-sale Securities	42,852	41,628
U.S. Government Bonds | Decommisioning Fund Investments | Quoted Prices In Active Markets For Identical Assets (Level 1)
Financial Instruments and Investments [Line Items]
Available-for-sale Securities	42,852	41,628
U.S. Government Bonds | Decommisioning Fund Investments | Significant Other Observable Inputs (Level 2)
Financial Instruments and Investments [Line Items]
Available-for-sale Securities	0	0
U.S. Government Bonds | Decommisioning Fund Investments | Significant Unobservable Inputs (Level 3)
Financial Instruments and Investments [Line Items]
Available-for-sale Securities	0	0
Collateralized Mortgage Backed Securities | Decommisioning Fund Investments
Financial Instruments and Investments [Line Items]
Available-for-sale Securities	20,632	17,771
Collateralized Mortgage Backed Securities | Decommisioning 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 | Decommisioning Fund Investments | Significant Other Observable Inputs (Level 2)
Financial Instruments and Investments [Line Items]
Available-for-sale Securities	20,632	17,771
Collateralized Mortgage Backed Securities | Decommisioning Fund Investments | Significant Unobservable Inputs (Level 3)
Financial Instruments and Investments [Line Items]
Available-for-sale Securities	0	0
Municipal Bonds | Decommisioning Fund Investments
Financial Instruments and Investments [Line Items]
Available-for-sale Securities	29,666	26,645
Municipal Bonds | Decommisioning 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 | Decommisioning Fund Investments | Significant Other Observable Inputs (Level 2)
Financial Instruments and Investments [Line Items]
Available-for-sale Securities	29,666	26,645
Municipal Bonds | Decommisioning Fund Investments | Significant Unobservable Inputs (Level 3)
Financial Instruments and Investments [Line Items]
Available-for-sale Securities	0	0
Corporate Debt Securities | Decommisioning Fund Investments
Financial Instruments and Investments [Line Items]
Available-for-sale Securities	21,003	18,678
Corporate Debt Securities | Decommisioning 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 | Decommisioning Fund Investments | Significant Other Observable Inputs (Level 2)
Financial Instruments and Investments [Line Items]
Available-for-sale Securities	21,003	18,678
Corporate Debt Securities | Decommisioning Fund Investments | Significant Unobservable Inputs (Level 3)
Financial Instruments and Investments [Line Items]
Available-for-sale Securities	0	0
Equity Securities | Decommisioning Fund Investments
Financial Instruments and Investments [Line Items]
Available-for-sale Securities	93,745	100,635
Equity Securities | Decommisioning Fund Investments | Quoted Prices In Active Markets For Identical Assets (Level 1)
Financial Instruments and Investments [Line Items]
Available-for-sale Securities	93,745	100,635
Equity Securities | Decommisioning Fund Investments | Significant Other Observable Inputs (Level 2)
Financial Instruments and Investments [Line Items]
Available-for-sale Securities	0	0
Equity Securities | Decommisioning Fund Investments | Significant Unobservable Inputs (Level 3)
Financial Instruments and Investments [Line Items]
Available-for-sale Securities	0	0
Common Collective Trust - Equity Funds | Decommisioning Fund Investments
Financial Instruments and Investments [Line Items]
Available-for-sale Securities	23,760	22,736
Common Collective Trust - Equity Funds | Decommisioning Fund Investments | Quoted Prices In Active Markets For Identical Assets (Level 1)
Financial Instruments and Investments [Line Items]
Available-for-sale Securities	0	0
Common Collective Trust - Equity Funds | Decommisioning Fund Investments | Significant Other Observable Inputs (Level 2)
Financial Instruments and Investments [Line Items]
Available-for-sale Securities	23,760	22,736
Common Collective Trust - Equity Funds | Decommisioning Fund Investments | Significant Unobservable Inputs (Level 3)
Financial Instruments and Investments [Line Items]
Available-for-sale Securities	0	0
Cash and Cash Equivalents | Decommisioning Fund Investments
Financial Instruments and Investments [Line Items]
Available-for-sale Securities	5,961	6,193
Cash and Cash Equivalents | Decommisioning Fund Investments | Quoted Prices In Active Markets For Identical Assets (Level 1)
Financial Instruments and Investments [Line Items]
Available-for-sale Securities	5,961	6,193
Cash and Cash Equivalents | Decommisioning Fund Investments | Significant Other Observable Inputs (Level 2)
Financial Instruments and Investments [Line Items]
Available-for-sale Securities	0	0
Cash and Cash Equivalents | Decommisioning Fund Investments | Significant Unobservable Inputs (Level 3)
Financial Instruments and Investments [Line Items]
Available-for-sale Securities	$0	$0