Evergy Kansas Central 10-K 25 Feb 15 2014 Q4 Annual report Financial data

Document_and_Entity_Informatio

Document and Entity Information Document (USD $)	12 Months Ended
	Dec. 31, 2014	Feb. 17, 2015	Jun. 30, 2014
Document Information [Line Items]
Document Type	10-K
Amendment Flag	FALSE
Document Period End Date	31-Dec-14
Document Fiscal Year Focus	2014
Document Fiscal Period Focus	Q4
Trading Symbol	wr
Entity Registrant Name	WESTAR ENERGY INC /KS
Entity Central Index Key	54507
Current Fiscal Year End Date	-19
Entity Filer Category	Large Accelerated Filer
Entity Common Stock, Shares Outstanding		132,137,563
Entity Well-known Seasoned Issuer	Yes
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Public Float			$4,936,929,569

Consolidated_Balance_Sheets

Consolidated Balance Sheets (USD $)	Dec. 31, 2014		Dec. 31, 2013
In Thousands, unless otherwise specified
CURRENT ASSETS:
Cash and cash equivalents	$4,556		$4,487
Accounts receivable, net of allowance for doubtful accounts	267,327		250,036
Fuel inventory and supplies	247,406		239,511
Deferred tax assets	29,636		37,954
Prepaid expenses	15,793		15,821
Regulatory assets	105,549		135,408
Other	30,655		23,608
Total Current Assets	700,922		706,825
Property, plant and equipment, net	8,162,908		7,551,916
OTHER ASSETS:
Regulatory assets	754,229		620,006
Nuclear decommissioning trust	185,016		175,625
Other	265,353		246,140
Total Other Assets	1,204,598		1,041,771
TOTAL ASSETS	10,347,001		9,597,138
CURRENT LIABILITIES:
Current maturities of long-term debt	0		250,000
Short-term debt	257,600		134,600
Accounts payable	219,351		233,351
Accrued dividends	44,971		43,604
Accrued taxes	74,356		69,769
Accrued interest	79,707		80,457
Regulatory liabilities	55,142		35,982
Other	90,571		80,184
Total Current Liabilities	849,631		955,426
LONG-TERM LIABILITIES:
Long-term debt, net	3,215,539		2,968,958
Deferred income taxes	1,475,487		1,363,148
Unamortized investment tax credits	211,040		192,265
Regulatory liabilities	288,343		293,574
Accrued employee benefits	532,622		331,558
Asset retirement obligations	230,668		160,682
Other	75,799		68,194
Total Long-Term Liabilities	6,196,063		5,573,181
COMMITMENTS AND CONTINGENCIES (See Notes 13 and 15)
Westar Energy, Inc. Shareholders' Equity:
Common stock, par value $5 per share; authorized 275,000,000 shares; issued and outstanding 126,503,748 shares and 125,698,396 shares, respective to each date	658,437		641,271
Paid-in capital	1,781,120		1,696,727
Retained earnings	855,299		724,776
Total Westar Energy, Inc. Shareholders' Equity	3,294,856		3,062,774
Noncontrolling Interests	6,451		5,757
Total Equity	3,301,307		3,068,531
TOTAL LIABILITIES AND EQUITY	10,347,001		9,597,138
Variable Interest Entity [Member]
CURRENT ASSETS:
Property, plant and equipment, net	278,573		296,626
CURRENT LIABILITIES:
Current maturities of long-term debt	27,933		27,479
Accrued interest	2,961	[1]	3,472	[1]
LONG-TERM LIABILITIES:
Long-term debt, net	$166,565		$194,802
[1]	Included in accrued interest on our consolidated balance sheets.

Consolidated_Balance_Sheets_Pa

Consolidated Balance Sheets Parenthetical (Parentheticals) (USD $)	Dec. 31, 2014	Dec. 31, 2013
In Thousands, except Share data, unless otherwise specified
Allowance for doubtful accounts receivable	$5,309	$4,596
Common stock, par value	$5	$5
Common stock, shares authorized	275,000,000	275,000,000
Common stock, shares issued	131,687,454	128,254,229
Common stock, shares outstanding	131,687,454	128,254,229

Consolidated_Statements_Of_Inc

Consolidated Statements Of Income (USD $)	12 Months Ended
In Thousands, except Share data, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
REVENUES	$2,601,703	$2,370,654	$2,261,470
OPERATING EXPENSES:
Fuel and purchased power	705,450	634,797	589,990
Network Transmission Cost	218,924	178,604	166,547
Operating and maintenance	367,188	359,060	342,055
Depreciation and amortization	286,442	272,593	270,464
Selling, general and administrative	250,439	224,133	226,012
Taxes, Miscellaneous	140,302	122,282	104,269
Total Operating Expenses	1,968,745	1,791,469	1,699,337
INCOME FROM OPERATIONS	632,958	579,185	562,133
OTHER INCOME (EXPENSE):
Investment earnings	10,622	10,056	7,411
Other income	31,522	35,609	35,378
Other expense	-18,389	-18,099	-19,987
Total Other Income (Expense)	23,755	27,566	22,802
Interest expense	183,118	182,167	176,337
INCOME BEFORE INCOME TAXES	473,595	424,584	408,598
Income tax expense	151,270	123,721	126,136
NET INCOME	322,325	300,863	282,462
Less: Net income attributable to noncontrolling interests	9,066	8,343	7,316
NET INCOME ATTRIBUTABLE TO WESTAR ENERGY	313,259	292,520	275,146
Preferred dividends	0	0	1,616
NET INCOME ATTRIBUTABLE TO COMMON STOCK	$313,259	$292,520	$273,530
Basic earnings per common share	$2.40	$2.29	$2.15
Diluted earnings per common share	$2.35	$2.27	$2.15
AVERAGE EQUIVALENT COMMON SHARES OUTSTANDING	130,014,941	127,462,994	126,711,869
DIVIDENDS DECLARED PER COMMON SHARE	$1.40	$1.36	$1.32

Consolidated_Statements_Of_Cas

Consolidated Statements Of Cash Flows (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
CASH FLOWS FROM (USED IN) OPERATING ACTIVITIES:
Net income	$322,325	$300,863	$282,462
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	286,442	272,593	270,464
Amortization of nuclear fuel	26,051	22,690	24,369
Amortization of deferred regulatory gain from sale-leaseback	-5,495	-5,495	-5,495
Amortization of corporate-owned life insurance	20,202	15,149	28,792
Non-cash compensation	7,280	8,188	7,255
Net deferred income taxes and credits	151,451	123,307	126,248
Stock-based compensation excess tax benefits	-875	-576	-1,698
Allowance for equity funds used during construction	-17,029	-14,143	-11,706
Changes in working capital items:
Accounts receivable	-17,291	-24,649	2,408
Fuel inventory and supplies	-8,773	10,124	-19,227
Prepaid expenses and other	36,717	-12,316	-3,630
Accounts payable	6,189	7,856	-19,161
Accrued taxes	6,596	14,218	11,937
Other current liabilities	-31,624	-52,829	-105,169
Changes in other assets	6,378	-4,167	13,015
Changes in other liabilities	35,811	41,990	-1,758
Cash Flows from Operating Activities	824,355	702,803	599,106
CASH FLOWS FROM (USED IN) INVESTING ACTIVITIES:
Additions to property, plant and equipment	-852,052	-780,098	-810,209
Purchase of securities within trusts	-9,075	-66,668	-20,473
Sale of securities within trusts	11,125	81,994	21,604
Investment in corporate-owned life insurance	-16,250	-17,724	-18,404
Proceeds from investment in corporate-owned life insurance	43,234	147,658	33,542
Proceeds from federal grant	0	876	4,775
Investment in affiliated company	-8,000	-4,947	-8,669
Other investing activities	-7,730	-2,992	497
Cash Flows used in Investing Activities	-838,748	-641,901	-797,337
CASH FLOWS FROM (USED IN) FINANCING ACTIVITIES:
Short-term debt, net	122,406	-205,241	52,900
Proceeds from long-term debt	417,943	492,347	541,374
Retirements of long-term debt	-427,500	-100,000	-220,563
Repayment of capital leases	-3,340	-2,995	-2,679
Borrowings against cash surrender value of corporate-owned life insurance	59,766	59,565	67,791
Repayment of borrowings against cash surrender value of corporate-owned life insurance	-41,249	-145,418	-34,838
Stock-based compensation excess tax benefits	875	576	1,698
Preferred stock redemption	0	0	-22,567
Issuance of common stock	87,669	32,906	6,996
Distributions to shareholders of noncontrolling interests	-1,030	-2,419	-3,295
Cash dividends paid	-171,507	-162,904	-158,182
Proceeds from (Payments for) Other Financing Activities	-2,092	-2,719	0
Cash Flows from (used in) Financing Activities	14,462	-62,244	200,521
NET INCREASE (DECREASE) IN CASH AND CASH EQUIVALENTS	69	-1,342	2,290
CASH AND CASH EQUIVALENTS:
Beginning of period	4,487	5,829	3,539
End of period	4,556	4,487	5,829
Variable Interest Entity [Member]
CASH FLOWS FROM (USED IN) FINANCING ACTIVITIES:
Retirements of long-term debt	($27,479)	($25,942)	($28,114)

Consolidated_Statements_Of_Cha

Consolidated Statements Of Changes In Equity (USD $)	Total	Cumulative Preferred Stock [Member]	Common Stock [Member]	Paid-In Capital [Member]	Retained Earnings [Member]	Noncontrolling Interests [Member]
In Thousands, except Share data
Beginning balance at Dec. 31, 2011	$2,800,741	$21,436	$628,492	$1,639,503	$501,216	$10,094
Beginning balance, shares at Dec. 31, 2011		214,363	125,698,396
Net income	282,462	0	0	0	275,146	7,316
Issuance of stock, value	6,996	0	1,212	5,784	0	0
Issuance of stock, shares		0	242,463
Issuance Of Stock For Comprensation And Reinvested Dividends, Shares			562,889
Issuance Of Stock For Compensation And Reinvested Dividends	9,089		2,815	6,274
Adjustments Related to Tax Withholding for Share-based Compensation	-3,490			-3,490
Stock redemption, shares		-214,363
Stock redemption, value	-21,436	-21,436
Preferred dividends	-1,616	0	0	0	-1,616	0
Dividends on common stock	-168,097		0	0	-168,097	0
Amortization of restricted stock	7,203	0	0	7,203
Stock compensation and tax benefit	1,698	0	0	1,698	0	0
Distributions to shareholders of noncontrolling interests	-3,295					-3,295
Ending balance at Dec. 31, 2012	2,910,255	0	632,519	1,656,972	606,649	14,115
Ending balance, shares at Dec. 31, 2012		0	126,503,748
Net income	300,863	0		0	292,520	8,343
Issuance of stock, value	32,906	0	6,282	26,624	0	0
Issuance of stock, shares		0	1,256,391
Issuance Of Stock For Comprensation And Reinvested Dividends, Shares			494,090
Issuance Of Stock For Compensation And Reinvested Dividends	9,641		2,470	7,171
Adjustments Related to Tax Withholding for Share-based Compensation	-2,719			-2,719
Preferred dividends	0
Dividends on common stock	-174,393	0	0	0	-174,393	0
Amortization of restricted stock	8,103			8,103
Stock compensation and tax benefit	576			-576
Noncontrolling Interest, Decrease from Deconsolidation	-14,282					-14,282
Distributions to shareholders of noncontrolling interests	-2,419					-2,419
Ending balance at Dec. 31, 2013	3,068,531	0	641,271	1,696,727	724,776	5,757
Ending balance, shares at Dec. 31, 2013		0	128,254,229
Net income	322,325	0		0	313,259	9,066
Issuance of stock, value	87,669	0	15,131	72,538	0	0
Issuance of stock, shares		0	3,026,239
Issuance Of Stock For Comprensation And Reinvested Dividends, Shares			406,986
Issuance Of Stock For Compensation And Reinvested Dividends	9,155		2,035	7,120
Adjustments Related to Tax Withholding for Share-based Compensation	-2,092			-2,092
Preferred dividends	0
Dividends on common stock	-182,736	0	0	0	-182,736	0
Amortization of restricted stock	7,193			7,193
Stock compensation and tax benefit	875			-875
Noncontrolling Interest, Decrease from Deconsolidation	-7,342					-7,342
Distributions to shareholders of noncontrolling interests	-1,030					-1,030
Stockholders' Equity, Other				-1,241
Ending balance at Dec. 31, 2014	$3,301,307	$0	$658,437	$1,781,120	$855,299	$6,451
Ending balance, shares at Dec. 31, 2014		0	131,687,454

Consolidated_Statements_Of_Cha1

Consolidated Statements Of Changes in Equity Parenthetical (Parentheticals) (USD $)

3 Months Ended

12 Months Ended

Dec. 31, 2014

Sep. 30, 2014

Jun. 30, 2014

Mar. 31, 2014

Dec. 31, 2013

Sep. 30, 2013

Jun. 30, 2013

Mar. 31, 2013

Dec. 31, 2014

Dec. 31, 2013

Dec. 31, 2012

DIVIDENDS DECLARED PER COMMON SHARE

$0.35

[1]

$0.35

[1]

$0.35

[1]

$0.35

[1]

$0.34

[1]

$0.34

[1]

$0.34

[1]

$0.34

[1]

$1.40

$1.36

$1.32

[1]

(a)Items are computed independently for each of the periods presented and the sum of the quarterly amounts may not equal the total for the year.

Description_Of_Business

Description Of Business	12 Months Ended
	Dec. 31, 2014
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Description Of Business	DESCRIPTION OF BUSINESS
	We are the largest electric utility in Kansas. Unless the context otherwise indicates, all references in this Annual Report on Form 10-K to "the company," "we," "us," "our" and similar words are to Westar Energy, Inc. and its consolidated subsidiaries. The term "Westar Energy" refers to Westar Energy, Inc., a Kansas corporation incorporated in 1924, alone and not together with its consolidated subsidiaries.
	We provide electric generation, transmission and distribution services to approximately 698,000

Summary_Of_Significant_Account

Summary Of Significant Accounting Policies	12 Months Ended
	Dec. 31, 2014
Accounting Policies [Abstract]
Summary Of Significant Accounting Policies	SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES
	Principles of Consolidation
	We prepare our consolidated financial statements in accordance with generally accepted accounting principles (GAAP) for the United States of America. Our consolidated financial statements include all operating divisions, majority owned subsidiaries and variable interest entities (VIEs) of which we maintain a controlling interest or are the primary beneficiary reported as a single reportable segment. Undivided interests in jointly-owned generation facilities are included on a proportionate basis. Intercompany accounts and transactions have been eliminated in consolidation.
	Use of Management's Estimates
	When we prepare our consolidated financial statements, we are required to make estimates and assumptions that affect the reported amounts of assets, liabilities, revenues and expenses, and related disclosure of contingent assets and liabilities, at the date of our consolidated financial statements and the reported amounts of revenues and expenses during the reporting period. We evaluate our estimates on an ongoing basis, including those related to depreciation, unbilled revenue, valuation of investments, forecasted fuel costs included in our retail energy cost adjustment (RECA) billed to customers, income taxes, pension and post-retirement benefits, our asset retirement obligations (AROs) including the decommissioning of Wolf Creek Generating Station (Wolf Creek), environmental issues, VIEs, contingencies and litigation. Actual results may differ from those estimates under different assumptions or conditions.
	Regulatory Accounting
	We apply accounting standards that recognize the economic effects of rate regulation. Accordingly, we have recorded regulatory assets and liabilities when required by a regulatory order or based on regulatory precedent. See Note 3, "Rate Matters and Regulation," for additional information regarding our regulatory assets and liabilities.
	Cash and Cash Equivalents
	We consider investments that are highly liquid and have maturities of three months or less when purchased to be cash equivalents.
	Fuel Inventory and Supplies
	We state fuel inventory and supplies at average cost. Following are the balances for fuel inventory and supplies stated separately.
		As of December 31,
		2014				2013
		(In Thousands)
	Fuel inventory	$	70,416			$	78,368
	Supplies	176,990				161,143
	Fuel inventory and supplies	$	247,406			$	239,511
	Property, Plant and Equipment
	We record the value of property, plant and equipment, including that of VIEs, at cost. For plant, cost includes contracted services, direct labor and materials, indirect charges for engineering and supervision and an allowance for funds used during construction (AFUDC). AFUDC represents the allowed cost of capital used to finance utility construction activity. We compute AFUDC by applying a composite rate to qualified construction work in progress. We credit other income (for equity funds) and interest expense (for borrowed funds) for the amount of AFUDC capitalized as construction cost on the accompanying consolidated statements of income as follows:
		Year Ended December 31,
		2014				2013			2012
		(Dollars In Thousands)
	Borrowed funds	$	12,044			$	11,706		$	10,399
	Equity funds	17,029				14,143			11,706
	Total	$	29,073			$	25,849		$	22,105
	Average AFUDC Rates	6.7		%		4.8		%	5		%
	We charge maintenance costs and replacements of minor items of property to expense as incurred, except for maintenance costs incurred for our planned refueling and maintenance outages at Wolf Creek. As authorized by regulators, we defer and amortize to expense ratably over the period between planned outages incremental maintenance costs incurred for such outages. When a unit of depreciable property is retired, we charge to accumulated depreciation the original cost less salvage value.
	Depreciation
	We depreciate utility plant using a straight-line method. The depreciation rates are based on an average annual composite basis using group rates that approximated 2.4% in 2014, 2.5% in 2013 and 2.6% in 2012.
	Depreciable lives of property, plant and equipment are as follows.
			Years
	Fossil fuel generating facilities		6	to	78
	Nuclear fuel generating facility		55	to	71
	Wind generating facilities		19	to	20
	Transmission facilities		15	to	75
	Distribution facilities		22	to	68
	Other		5	to	30
	Nuclear Fuel
	We record as property, plant and equipment our share of the cost of nuclear fuel used in the process of refinement, conversion, enrichment and fabrication. We reflect this at original cost and amortize such amounts to fuel expense based on the quantity of heat consumed during the generation of electricity as measured in millions of British thermal units (MMBtu). The accumulated amortization of nuclear fuel in the reactor was $72.3 million as of December 31, 2014, and $46.2 million as of December 31, 2013. The cost of nuclear fuel charged to fuel and purchased power expense was $27.3 million in 2014, $26.5 million in 2013 and $28.3 million in 2012.
	Cash Surrender Value of Life Insurance
	We recorded on our consolidated balance sheets in other long-term assets the following amounts related to corporate-owned life insurance (COLI) policies.
		As of December 31,
		2014				2013
		(In Thousands)
	Cash surrender value of policies	$	1,306,777			$	1,289,457
	Borrowings against policies	(1,173,956		)		(1,156,341		)
	Corporate-owned life insurance, net	$	132,821			$	133,116
	We record as income increases in cash surrender value and death benefits. We offset against policy income the interest expense that we incur on policy loans. Income from death benefits is highly variable from period to period.
	Revenue Recognition
	We record revenue at the time we deliver electricity to customers. We determine the amounts delivered to individual customers through systematic monthly readings of customer meters. At the end of each month, we estimate how much electricity we have delivered since the prior meter reading and record the corresponding unbilled revenue.
	Our unbilled revenue estimate is affected by factors including fluctuations in energy demand, weather, line losses and changes in the composition of customer classes. We recorded estimated unbilled revenue of $61.0 million as of December 31, 2014, and $60.1 million as of December 31, 2013.
	Allowance for Doubtful Accounts
	We determine our allowance for doubtful accounts based on the age of our receivables. We charge receivables off when they are deemed uncollectible, which is based on a number of factors including specific facts surrounding an account and management's judgment.
	Income Taxes
	We use the asset and liability method of accounting for income taxes. Under this method, we recognize deferred tax assets and liabilities for the future tax consequences attributable to temporary differences between the financial statement carrying amounts and the tax basis of existing assets and liabilities. We recognize the future tax benefits to the extent that realization of such benefits is more likely than not. We amortize deferred investment tax credits over the lives of the related properties as required by tax laws and regulatory practices. We recognize production tax credits in the year that electricity is generated to the extent that realization of such benefits is more likely than not.
	We record deferred tax assets to the extent capital losses, operating losses, or tax credits will be carried forward to future periods. However, when we believe based on available evidence that we do not, or will not, have sufficient future capital gains or taxable income in the appropriate taxing jurisdiction to realize the entire benefit during the applicable carryforward period, we record a valuation allowance against the deferred tax asset.
	The application of income tax law is complex. Laws and regulations in this area are voluminous and often ambiguous. Accordingly, we must make judgments regarding income tax exposure. Interpretations of and guidance surrounding income tax laws and regulations change over time. As a result, changes in our judgments can materially affect amounts we recognize in our consolidated financial statements. See Note 10, "Taxes," for additional detail on our accounting for income taxes.
	Sales Tax
	We account for the collection and remittance of sales tax on a net basis. As a result, we do not reflect sales tax in our consolidated statements of income.
	Earnings Per Share
	We have participating securities in the form of unvested restricted share units (RSUs) with nonforfeitable rights to dividend equivalents that receive dividends on an equal basis with dividends declared on common shares. As a result, we apply the two-class method of computing basic and diluted earnings per share (EPS).
	To compute basic EPS, we divide the earnings allocated to common stock by the weighted average number of common shares outstanding. Diluted EPS includes the effect of potential issuances of common shares resulting from our forward sale agreements and RSUs with forfeitable rights to dividend equivalents. We compute the dilutive effect of potential issuances of common shares using the treasury stock method.
	The following table reconciles our basic and diluted EPS from net income.
		Year Ended December 31,
	2014				2013			2012
	(Dollars In Thousands, Except Per Share Amounts)
Net income	$	322,325			$	300,863		$	282,462
Less: Net income attributable to noncontrolling interests	9,066				8,343			7,316
Net income attributable to Westar Energy, Inc.	313,259				292,520			275,146
Less: Preferred dividends	—				—			1,616
Net income allocated to RSUs	790				810			778
Net income allocated to common stock	$	312,469			$	291,710		$	272,752
Weighted average equivalent common shares outstanding – basic	130,014,941				127,462,994			126,711,869
Effect of dilutive securities:
RSUs	181,397				17,195			97,757
Forward sale agreements	2,628,187				818,505			89,160
Weighted average equivalent common shares outstanding – diluted (a)	132,824,525				128,298,694			126,898,786
Earnings per common share, basic	$	2.4			$	2.29		$	2.15
Earnings per common share, diluted	$	2.35			$	2.27		$	2.15
_______________
(a)	For the years ended December 31, 2014, 2013 and 2012, we had no antidilutive securities.
Supplemental Cash Flow Information
	Year Ended December 31,
	2014				2013			2012
	(In Thousands)
CASH PAID FOR (RECEIVED FROM):
Interest on financing activities, net of amount capitalized	$	160,292			$	148,691		$	143,564
Interest on financing activities of VIEs	12,183				13,892			16,214
Income taxes, net of refunds	458				(11		)	(4,378		)
NON-CASH INVESTING TRANSACTIONS:
Property, plant and equipment additions	143,192				127,544			89,354
Property, plant and equipment of VIEs	(7,342		)		(14,282		)	—
NON-CASH FINANCING TRANSACTIONS:
Issuance of common stock for reinvested dividends and compensation plans	9,155				9,641			9,089
Deconsolidation of VIEs	(7,342		)		(14,282		)	—
Assets acquired through capital leases	8,717				334			10,683
New Accounting Pronouncements
We prepare our consolidated financial statements in accordance with GAAP for the United States of America. To address current issues in accounting, regulatory bodies have issued the following new accounting pronouncements that may affect our accounting and/or disclosure.
Extraordinary and Unusual Items
In January 2015, the Financial Accounting Standards Board (FASB) issued guidance that eliminates the accounting concept of extraordinary items. The objective of the new guidance is to reduce complexity in accounting standards while maintaining or improving the usefulness of information provided. The guidance is effective for fiscal years beginning after December 15, 2015, with early adoption permitted. We have elected to adopt effective January 1, 2015, without a material impact to our financial statements.
Revenue Recognition
In May 2014, the FASB issued guidance that addresses revenue from contracts with customers. The objective of the new guidance is to establish principles to report useful information to users of financial statements about the nature, amount, timing and uncertainty of revenue from contracts with customers. This guidance is effective for fiscal years beginning after December 15, 2016. Early application of the standard is not permitted. The standard permits the use of either the retrospective application or cumulative effect transition method. We have not yet selected a transition method or determined the impact on our consolidated financial statements but we do not expect it to be material.

Rate_Matters_And_Regulation

Rate Matters And Regulation	12 Months Ended
	Dec. 31, 2014
Regulated Operations [Abstract]
Rate Matters And Regulation	RATE MATTERS AND REGULATION
	Regulatory Assets and Regulatory Liabilities
	Regulatory assets represent incurred costs that have been deferred because they are probable of future recovery in customer prices. Regulatory liabilities represent probable future reductions in revenue or refunds to customers through the price setting process. Regulatory assets and liabilities reflected on our consolidated balance sheets are as follows.
		As of December 31,
		2014		2013
		(In Thousands)
	Regulatory Assets:
	Deferred employee benefit costs	$	435,590	$	277,122
	Amounts due from customers for future income taxes, net	153,984		163,742
	Depreciation	68,422		71,047
	Debt reacquisition costs	61,079		63,882
	Ad valorem tax	39,428		34,492
	Treasury yield hedges	26,614		27,594
	Asset retirement obligations	26,106		23,555
	Disallowed plant costs	15,809		15,964
	Wolf Creek outage	11,165		29,026
	Energy efficiency program costs	8,933		14,477
	Retail energy cost adjustment	—		22,138
	Other regulatory assets	12,648		12,375
	Total regulatory assets	$	859,778	$	755,414
	Regulatory Liabilities:
	Removal costs	$	88,242	$	114,148
	Deferred regulatory gain from sale leaseback	81,055		86,551
	Nuclear decommissioning	43,641		43,272
	Retail energy cost adjustment	33,274		15,414
	Jurisdictional allowance for funds used during construction	33,103		7,893
	La Cygne leasehold dismantling costs	22,918		20,505
	Other post-retirement benefits costs	15,473		19,000
	Kansas tax credits	12,725		11,076
	Gain on sale of oil	2,337		4,278
	Fuel supply and electricity contracts	1,738		2,635
	Other regulatory liabilities	8,979		4,784
	Total regulatory liabilities	$	343,485	$	329,556
	Below we summarize the nature and period of recovery for each of the regulatory assets listed in the table above.
	•	Deferred employee benefit costs: Includes $399.8 million for pension and post-retirement benefit obligations and $35.8 million for actual pension expense in excess of the amount of such expense recognized in setting our prices. The increase from 2013 to 2014 is attributable primarily to a decrease in the discount rates used to calculate our and Wolf Creek's pension benefit obligations and the adoption of updated mortality tables. During 2015, we will amortize to expense approximately $39.5 million of the benefit obligations and approximately $9.8 million of the excess pension expense. We are amortizing the excess pension expense over a five-year period. We do not earn a return on this asset.
	•	Amounts due from customers for future income taxes, net: In accordance with various orders, we have reduced our prices to reflect the income tax benefits associated with certain income tax deductions, thereby passing on these benefits to customers at the time we receive them. We believe it is probable that the net future increases in income taxes payable will be recovered from customers when these temporary income tax benefits reverse in future periods. We have recorded a regulatory asset, net of the regulatory liability, for these amounts. We also have recorded a regulatory liability for our obligation to customers for income taxes recovered in earlier periods when corporate income tax rates were higher than current income tax rates. This benefit will be returned to customers as these temporary differences reverse in future periods. The income tax-related regulatory assets and liabilities as well as unamortized investment tax credits are also temporary differences for which deferred income taxes have been provided. These items are measured by the expected cash flows to be received or settled in future prices. We do not earn a return on this net asset.
	•	Depreciation: Represents the difference between regulatory depreciation expense and depreciation expense we record for financial reporting purposes. We earn a return on this asset and amortize the difference over the life of the related plant.
	•	Debt reacquisition costs: Includes costs incurred to reacquire and refinance debt. These costs are amortized over the term of the new debt. We do not earn a return on this asset.
	•	Ad valorem tax: Represents actual costs incurred for property taxes in excess of amounts collected in our prices. We expect to recover these amounts in our prices over a one-year period. We do not earn a return on this asset.
	•	Treasury yield hedges: Represents the effective portion of losses on treasury yield hedge transactions. This amount will be amortized to interest expense over the term of the related debt. See Note 4, "Financial Instruments and Trading Securities—Cash Flow Hedges," for additional information regarding our treasury yield hedge transactions. We do not earn a return on this asset.
	•	Asset retirement obligations: Represents amounts associated with our AROs as discussed in Note 14, "Asset Retirement Obligations." We recover these amounts over the life of the related plant. We do not earn a return on this asset.
	•	Disallowed plant costs: Originally there was a decision to disallow certain costs related to the Wolf Creek plant. Subsequently, in 1987, the KCC revised its original conclusion and provided for recovery of an indirect disallowance with no return on investment. This regulatory asset represents the present value of the future expected revenues to be provided to recover these costs, net of the amounts amortized.
	•	Wolf Creek outage: We defer the expenses associated with Wolf Creek's scheduled refueling and maintenance outages and amortize these expenses during the period between planned outages. We do not earn a return on this asset.
	•	Energy efficiency program costs: We accumulate and defer for future recovery costs related to our various energy efficiency programs. We will amortize such costs over a one-year period. We do not earn a return on this asset.
	•	Retail energy cost adjustment: We are allowed to adjust our retail prices to reflect changes in the cost of fuel and purchased power needed to serve our customers. This item represents the actual cost of fuel consumed in producing electricity and the cost of purchased power in excess of the amounts we have collected from customers. We expect to recover in our prices this shortfall over a one-year period. We do not earn a return on this asset.
	•	Other regulatory assets: Includes various regulatory assets that individually are small in relation to the total regulatory asset balance. Other regulatory assets have various recovery periods. We do not earn a return on any of these assets.
	Below we summarize the nature and period of amortization for each of the regulatory liabilities listed in the table above.
	•	Removal costs: Represents amounts collected, but not yet spent, to dispose of plant assets that do not represent legal retirement obligations. This liability will be discharged as removal costs are incurred.
	•	Deferred regulatory gain from sale leaseback: Represents the gain KGE recorded on the 1987 sale and leaseback of its 50% interest in La Cygne Generating Station (La Cygne) unit 2. We amortize the gain over the lease term.
	•	Nuclear decommissioning: We have a legal obligation to decommission Wolf Creek at the end of its useful life. This amount represents the difference between the fair value of the assets held in a decommissioning trust and the amount recorded for the accumulated accretion and depreciation expense associated with our ARO. See Note 4, 5 and 14, "Financial Instruments and Trading Securities," "Financial Investments" and "Asset Retirement Obligations," respectively, for information regarding our nuclear decommissioning trust (NDT) and our ARO.
	•	Retail energy cost adjustment: We are allowed to adjust our retail prices to reflect changes in the cost of fuel and purchased power needed to serve our customers. We bill customers based on our estimated costs. This item represents the amount we collected from customers that was in excess of our actual cost of fuel and purchased power. We will refund to customers this excess recovery over a one-year period.
	•	Jurisdictional allowance for funds used during construction: This item represents AFUDC that is accrued subsequent to the time the associated construction charges are included in our rates and prior to the time the charges are placed in service. The AFUDC is amortized to depreciation expense over the useful life of the asset that is placed in service.
	•	La Cygne leasehold dismantling costs: We are contractually obligated to dismantle a portion of La Cygne unit 2. This item represents amounts collected but not yet spent to dismantle this unit and the obligation will be discharged as we dismantle the unit.
	•	Other post-retirement benefits costs: Represents amount of other post-retirement benefits expense recognized in setting our prices in excess of actual other post-retirement benefits expense. We amortize the amount over a five-year period.
	•	Kansas tax credits: This item represents Kansas tax credits on investments in utility plant. Amounts will be credited to customers subsequent to their realization over the remaining lives of the utility plant giving rise to the tax credits.
	•	Gain on sale of oil: We discontinued the use of a certain type of oil in our plants. As a result, we sold this oil inventory for a gain. This item represents the remaining portion of the gain that will be refunded to customers over a three-year period.
	•	Fuel supply and electricity contracts: We use fair value accounting for some of our fuel supply and electricity contracts. This represents the non-cash net gain position on fuel supply and electricity contracts that are recorded at fair value. Under the RECA, fuel supply contract market gains accrue to the benefit of our customers.
	•	Other regulatory liabilities: Includes various regulatory liabilities that individually are relatively small in relation to the total regulatory liability balance. Other regulatory liabilities will be credited over various periods.
	KCC Proceedings
	General and Abbreviated Rate Reviews
	We, staff of the Kansas Corporation Commission (KCC) and a consumer advocate joined in a request filed with the KCC to defer depreciation expense and carrying costs related to our capital investment associated with environmental upgrades at La Cygne until new retail prices become effective following a general rate case expected to be filed in March 2015. We estimate our share of these deferred costs will be approximately $20.0 million and we expect to begin deferring these costs in March 2015. In September 2014, the KCC issued an order approving the joint application that will allow us to include these deferred costs in our next general rate case, which is expected to increase our annual revenues by approximately $4.0 million.
	In November 2013, the KCC issued an order allowing us to adjust our prices to include the additional investment in the La Cygne environmental upgrades, as discussed below, and to reflect cost reductions elsewhere. The new prices were expected to increase our annual retail revenues by approximately $30.7 million.
	In April 2012, the KCC issued an order expected to increase our annual retail revenues by approximately $50.0 million. In addition, we revised our depreciation rates to reflect changes in the estimated useful lives of some of our depreciable assets. The change in estimate decreased annual depreciation expense by $43.6 million. The new prices were effective shortly after having received the order.
	Environmental Costs
In August 2011, the KCC issued an order ruling that Kansas City Power & Light Company's (KCPL) decision to make environmental upgrades at La Cygne to comply with environmental regulations is prudent and the $1.2 billion project cost estimate is reasonable. We have a 50% interest in La Cygne and intervened in the proceeding. The KCC denied our request to collect our approximately $610.0 million share of the capital investment for the environmental upgrades through our environmental cost recovery rider (ECRR). However, as noted above, we received an order regarding an abbreviated rate review to update our prices to include a portion of the capital costs associated with the project. We will request to collect our remaining investment in La Cygne environmental upgrades as part of a general rate case expected to be filed in March 2015.
We also make annual filings with the KCC to adjust our prices to include costs associated with investments in air quality equipment made during the prior year. In the most recent three years, the KCC issued orders related to such filings allowing us to increase our annual retail revenues by approximately:
•	$11.0 million effective in June 2014;
•	$27.3 million effective in June 2013; and
•	$19.5 million effective in June 2012.
Transmission Costs
We make annual filings with the KCC to adjust our prices to include updated transmission costs as reflected in our transmission formula rate discussed below. In the most recent three years, the KCC issued orders related to such filings allowing us to increase our annual retail revenues by approximately:
•	$41.0 million effective in April 2014;
•	$11.8 million effective in March 2013; and
•	$36.7 million effective in April 2012.
Energy Efficiency
We make annual filings with the KCC to adjust our prices to include previously deferred amounts associated with various energy efficiency programs. In the most recent three years, the KCC issued orders related to such filings authorizing us to adjust our annual retail revenues by approximately:
•	$5.0 million decrease effective in November 2014;
•	$1.3 million decrease effective in November 2013; and
•	$1.1 million increase effective in October 2012.
Property Tax Surcharge
We make annual filings with the KCC to adjust our prices to include the cost incurred for property taxes. In the most recent three years, the KCC issued orders related to such filings allowing us to increase our annual retail revenues by approximately:
•	$12.7 million effective in January 2014;
•	$15.2 million effective in January 2013; and
•	$5.9 million effective in January 2012.
FERC Proceedings
In October of each year, we post an updated transmission formula rate that includes projected transmission capital expenditures and operating costs for the following year. This rate provides the basis for our annual request with the KCC to adjust our retail prices to include updated transmission costs as noted above. In the most recent three years, we posted our transmission formula rate which was expected to increase our annual transmission revenues by approximately:
•	$44.3 million effective in January 2014;
•	$12.2 million effective in January 2013; and
•	$38.2 million effective in January 2012.

Financial_Instruments_and_Trad

Financial Instruments and Trading Securities	12 Months Ended
	Dec. 31, 2014
Financial And Derivative Instruments and Trading Securities [Abstract]
Financial And Derivative Instruments, Trading Securities, Energy Marketing And Risk Management	FINANCIAL INSTRUMENTS AND TRADING SECURITIES
	Values of Financial and Derivative Instruments
	GAAP establishes a hierarchical framework for disclosing the transparency of the inputs utilized in measuring assets and liabilities at fair value. Our assessment of the significance of a particular input to the fair value measurement requires judgment and may affect the classification of assets and liabilities within the fair value hierarchy levels. The three levels of the hierarchy and examples are as follows:
	•	Level 1 - Quoted prices are available in active markets for identical assets or liabilities. The types of assets and liabilities included in level 1 are highly liquid and actively traded instruments with quoted prices, such as equities listed on public exchanges.
	•	Level 2 - Pricing inputs are not quoted prices in active markets, but are either directly or indirectly observable. The types of assets and liabilities included in level 2 are typically measured at net asset value, comparable to actively traded securities or contracts, such as treasury securities with pricing interpolated from recent trades of similar securities, or priced with models using highly observable inputs.
	•	Level 3 - Significant inputs to pricing have little or no transparency. The types of assets and liabilities included in level 3 are those with inputs requiring significant management judgment or estimation. Level 3 includes investments in private equity, real estate securities and other alternative investments, which are measured at net asset value.
	We record cash and cash equivalents, short-term borrowings and variable rate debt on our consolidated balance sheets at cost, which approximates fair value. We measure the fair value of fixed rate debt, a level 2 measurement, based on quoted market prices for the same or similar issues or on the current rates offered for instruments of the same remaining maturities and redemption provisions. The recorded amount of accounts receivable and other current financial instruments approximates fair value.
	All of our level 2 investments are held in investment funds that are measured at fair value using daily net asset values. In addition, we maintain certain level 3 investments in private equity, alternative investments and real estate securities that are also measured at fair value using net asset value, but require significant unobservable market information to measure the fair value of the underlying investments. The underlying investments in private equity are measured at fair value utilizing both market- and income-based models, public company comparables, investment cost or the value derived from subsequent financings. Adjustments are made when actual performance differs from expected performance; when market, economic or company-specific conditions change; and when other news or events have a material impact on the security. The underlying alternative investments include collateralized debt obligations, mezzanine debt and a variety of other investments. The fair value of these investments is measured using a variety of primarily market-based models utilizing inputs such as security prices, maturity, call features, ratings and other developments related to specific securities. The underlying real estate investments are measured at fair value using a combination of market- and income-based models utilizing market discount rates, projected cash flows and the estimated value into perpetuity.
	We measure fair value based on information available as of the measurement date. The following table provides the carrying values and measured fair values of our fixed-rate debt.
		As of December 31, 2014					As of December 31, 2013
		Carrying Value			Fair Value		Carrying Value			Fair Value
		(In Thousands)
	Fixed-rate debt	$	3,105,000		$	3,488,410	$	3,102,500		$	3,294,209
	Fixed-rate debt of VIEs	194,204			213,579		221,682			241,241
	Recurring Fair Value Measurements
	The following table provides the amounts and their corresponding level of hierarchy for our assets that are measured at fair value.
	As of December 31, 2014	Level 1			Level 2		Level 3			Total
		(In Thousands)
	Assets:
	Nuclear Decommissioning Trust:
	Domestic equity funds	$	—		$	54,925	$	6,047		$	60,972
	International equity funds	—			30,791		—			30,791
	Core bond fund	—			19,289		—			19,289
	High-yield bond fund	—			13,198		—			13,198
	Emerging market bond fund	—			10,988		—			10,988
	Other fixed income fund	—			4,779		—			4,779
	Combination debt/equity/other funds	—			18,141		—			18,141
	Alternative investment fund	—			—		16,970			16,970
	Real estate securities fund	—			—		9,548			9,548
	Cash equivalents	340			—		—			340
	Total Nuclear Decommissioning Trust	340			152,111		32,565			185,016
	Trading Securities:
	Domestic equity funds	—			18,698		—			18,698
	International equity fund	—			4,252		—			4,252
	Core bond fund	—			12,379		—			12,379
	Cash equivalents	168			—		—			168
	Total Trading Securities	168			35,329		—			35,497
	Total Assets Measured at Fair Value	$	508		$	187,440	$	32,565		$	220,513
	As of December 31, 2013
	Assets:
	Nuclear Decommissioning Trust:
	Domestic equity funds	$	—		$	49,957	$	5,817		$	55,774
	International equity funds	—			31,816		—			31,816
	Core bond fund	—			18,107		—			18,107
	High-yield bond fund	—			12,902		—			12,902
	Emerging market bond fund	—			11,055		—			11,055
	Other fixed income fund	—			4,690		—			4,690
	Combination debt/equity/other funds	—			17,093		—			17,093
	Alternative investment fund	—			—		15,675			15,675
	Real estate securities fund	—			—		8,511			8,511
	Cash equivalents	2			—		—			2
	Total Nuclear Decommissioning Trust	2			145,620		30,003			175,625
	Trading Securities:
	Domestic equity funds	—			18,075		—			18,075
	International equity fund	—			4,519		—			4,519
	Core bond fund	—			12,166		—			12,166
	Cash equivalents	166			—		—			166
	Total Trading Securities	166			34,760		—			34,926
	Total Assets Measured at Fair Value	$	168		$	180,380	$	30,003		$	210,551
	The following table provides reconciliations of assets held in the NDT measured at fair value using significant level 3 inputs for the years ended December 31, 2014 and 2013.
		Domestic			Alternative Investment Fund		Real Estate			Net
		Equity Funds					Securities Fund			Balance
		(In Thousands)
	Balance as of December 31, 2013	$	5,817		$	15,675	$	8,511		$	30,003
Total realized and unrealized gains included in:
Regulatory liabilities	391			1,295		1,037			2,723
Purchases	335			—		351			686
Sales	(496		)	—		(351		)	(847		)
Balance as of December 31, 2014	$	6,047		$	16,970	$	9,548		$	32,565
Balance as of December 31, 2012	$	4,899		$	—	$	7,865		$	12,764
Total realized and unrealized gains included in:
Regulatory liabilities	940			675		646			2,261
Purchases	341			15,000		287			15,628
Sales	(363		)	—		(287		)	(650		)
Balance as of December 31, 2013	$	5,817		$	15,675	$	8,511		$	30,003
Portions of the gains and losses contributing to changes in net assets in the above table are unrealized. The following table summarizes the unrealized gains and losses we recorded to regulatory liabilities on our consolidated financial statements during the years ended December 31, 2014 and 2013, attributed to level 3 assets and liabilities.
	Domestic			Alternative Investment Fund		Real Estate			Net
	Equity Funds					Securities Fund			Balance
	(In Thousands)
Year ended December 31, 2014	$	(105	)	$	1,296	$	685		$	1,876
Year ended December 31, 2013	577			675		359			1,611
Some of our investments in the NDT and our trading securities portfolio are measured at net asset value, do not have readily determinable fair values and are either with investment companies or companies that follow accounting guidance consistent with investment companies. In certain situations these investments may have redemption restrictions. The following table provides additional information on these investments.
	As of December 31, 2014					As of December 31, 2013						As of December 31, 2014
	Fair Value			Unfunded		Fair Value			Unfunded			Redemption	Length of
				Commitments					Commitments			Frequency	Settlement
	(In Thousands)
Nuclear Decommissioning Trust:
Domestic equity funds	$	6,047		$	2,348	$	5,817		$	2,683		(a)	(a)
Alternative investment fund	16,970			—		15,675			—			(b)	(b)
Real estate securities fund	9,548			—		8,511			—			Quarterly	80 days
Total Nuclear Decommissioning Trust	$	32,565		$	2,348	$	30,003		$	2,683
Trading Securities:
Domestic equity funds	$	18,698		$	—	$	18,075		$	—		Upon Notice	1 day
International equity funds	4,252			—		4,519			—			Upon Notice	1 day
Core bond fund	12,379			—		12,166			—			Upon Notice	1 day
Total Trading Securities	35,329			—		34,760			—
Total	$	67,894		$	2,348	$	64,763		$	2,683
_______________
(a)	This investment is in three long-term private equity funds that do not permit early withdrawal. Our investments in these funds cannot be distributed until the underlying investments have been liquidated which may take years from the date of initial liquidation. Two funds have begun to make distributions. Our initial investment in the third fund occurred in the third quarter of 2013. This fund's term will be 15 years, subject to the general partner's right to extend the term for up to three additional one-year periods.
(b)	This fund has an initial lock-up period of 24 months, which began in April 2013. Redemptions are allowed, on a quarterly basis, after 24 months at the sole discretion of the fund's board of directors. A 65-day notice of redemption is required. There is a holdback on final redemptions.
Derivative Instruments
Cash Flow Hedges
In 2011, we entered into treasury yield hedge transactions to hedge our interest rate risk associated with a $125.0 million portion of a forecasted issuance of fixed rate debt. These transactions were designated and qualified as cash flow hedges and measured at fair value by estimating the net present value of a series of payments using market-based models with observable inputs such as the spread between the 30-year U.S Treasury bill yield and the contracted, fixed yield. As a result of regulatory accounting treatment, we report the effective portion of the gains or losses on these derivative instruments as a regulatory liability or regulatory asset and amortize such amounts to interest expense over the term of the related debt. In 2012, we settled the treasury yield hedge transactions for a cost of $29.7 million, which will be amortized to interest expense over the 30-year term of the debt issued in March 2012. See Note 9, "Long-Term Debt" for additional information regarding the debt issuance. As of December 31, 2014 and 2013, we had recorded $26.6 million and $27.6 million, respectively, as a regulatory asset.
Price Risk
We use various types of fuel, including coal, natural gas, uranium and diesel to operate our plants and also purchase power to meet customer demand. Our prices and consolidated financial results are exposed to market risks from commodity price changes for electricity and other energy-related products as well as from interest rates. Volatility in these markets impacts our costs of purchased power, costs of fuel for our generating plants and our participation in energy markets. We strive to manage our customers' and our exposure to these market risks through regulatory, operating and financing activities and, when we deem appropriate, we economically hedge a portion of these risks through the use of derivative financial instruments for non-trading purposes.
Interest Rate Risk
We have entered into numerous fixed and variable rate debt obligations. For details, see Note 9, "Long-Term Debt." We manage our interest rate risk related to these debt obligations by limiting our exposure to variable interest rate debt, diversifying maturity dates and entering into treasury yield hedge transactions. We may also use other financial derivative instruments such as interest rate swaps.

Financial_Investments

Financial Investments	12 Months Ended
	Dec. 31, 2014
Investments [Abstract]
Financial Investments	FINANCIAL INVESTMENTS
	We report our investments in equity and debt securities at fair value and use the specific identification method to determine their realized gains and losses. We classify these investments as either trading securities or available-for-sale securities as described below.
	Trading Securities
	We hold equity and debt investments which we classify as trading securities in a trust used to fund certain retirement benefit obligations. These obligations totaled $29.8 million and $27.0 million as of December 31, 2014 and 2013, respectively. For additional information on our benefit obligations, see Note 11, "Employee Benefit Plans."
	As of December 31, 2014 and 2013, we measured the fair value of trust assets at $35.5 million and $34.9 million, respectively. We include unrealized gains or losses on these securities in investment earnings on our consolidated statements of income. For the years ended December 31, 2014, 2013 and 2012, we recorded unrealized gains of $2.6 million, $6.7 million and $4.1 million, respectively.
	Available-for-Sale Securities
	We hold investments in a trust for the purpose of funding the decommissioning of Wolf Creek. We have classified these investments as available-for-sale and have recorded all such investments at their fair market value as of December 31, 2014 and 2013.
	Using the specific identification method to determine cost, we realized gains on our available-for-sale securities of $0.1 million in 2014, $5.3 million in 2013 and $0.6 million in 2012. We record net realized and unrealized gains and losses in regulatory liabilities on our consolidated balance sheets. This reporting is consistent with the method we use to account for the decommissioning costs we recover in our prices. Gains or losses on assets in the trust fund are recorded as increases or decreases, respectively, to regulatory liabilities and could result in lower or higher funding requirements for decommissioning costs, which we believe would be reflected in the prices paid by our customers.
	The following table presents the cost, gross unrealized gains and losses, fair value and allocation of investments in the NDT fund as of December 31, 2014 and 2013.
						Gross Unrealized
	Security Type		Cost			Gain			Loss				Fair Value			Allocation
			(Dollars In Thousands)
	As of December 31, 2014
	Domestic equity funds		$	46,126		$	14,853		$	(7	)		$	60,972		33	%
	International equity funds		27,521			3,683			(413		)		30,791			17	%
	Core bond fund		18,811			478			—				19,289			10	%
	High-yield bond fund		13,342			—			(144		)		13,198			7	%
	Emerging market bond fund		12,556			—			(1,568		)		10,988			6	%
	Other fixed income fund		4,798			—			(19		)		4,779			3	%
	Combination debt/equity/other funds		14,975			3,786			(620		)		18,141			10	%
	Alternative investment fund		15,000			1,970			—				16,970			9	%
	Real estate securities fund		10,619			—			(1,071		)		9,548			5	%
	Cash equivalents		340			—			—				340			<1%
	Total		$	164,088		$	24,770		$	(3,842	)		$	185,016		100	%
	As of December 31, 2013
	Domestic equity funds		$	40,976		$	14,799		$	(1	)		$	55,774		32	%
	International equity funds		26,581			5,266			(31		)		31,816			18	%
	Core bond fund		18,287			—			(180		)		18,107			10	%
	High-yield bond fund		12,275			627			—				12,902			7	%
	Emerging market bond fund		12,207			—			(1,152		)		11,055			6	%
	Other fixed income fund		4,684			6			—				4,690			3	%
	Combination debt/equity/other funds		14,964			2,380			(251		)		17,093			10	%
	Alternative investment fund		15,000			675			—				15,675			9	%
	Real estate securities fund		10,268			—			(1,757		)		8,511			5	%
	Cash equivalents		2			—			—				2			<1%
	Total		$	155,244		$	23,753		$	(3,372	)		$	175,625		100	%
	The following table presents the fair value and the gross unrealized losses of the available-for-sale securities held in the NDT fund aggregated by investment category and the length of time that individual securities have been in a continuous unrealized loss position as of December 31, 2014 and 2013.
		Less than 12 Months						12 Months or Greater							Total
		Fair Value			Gross			Fair Value				Gross			Fair Value			Gross
					Unrealized							Unrealized						Unrealized
					Losses							Losses						Losses
		(In Thousands)
	As of December 31, 2014
	Domestic equity funds	$	—		$	—		$	263			$	(7	)	$	263		$	(7	)
	International equity funds	5,905			(413		)	—				—			5,905			(413		)
	High-yield bond fund	13,198			(144		)	—				—			13,198			(144		)
	Emerging market bond fund	—			—			10,988				(1,568		)	10,988			(1,568		)
	Other fixed income fund	4,779			(19		)	—				—			4,779			(19		)
	Combination debt/equity/other funds	—			—			5,892				(620		)	5,892			(620		)
	Real estate securities fund	—			—			9,548				(1,071		)	9,548			(1,071		)
	Total	$	23,882		$	(576	)	$	26,691			$	(3,266	)	$	50,573		$	(3,842	)
	As of December 31, 2013
	Domestic equity funds	$	59		$	(1	)	$	—			$	—		$	59		$	(1	)
	International equity funds	6,244			(31		)	—				—			6,244			(31		)
	Core bond fund	18,107			(180		)	—				—			18,107			(180		)
	Emerging market bond fund	11,055			(1,152		)	—				—			11,055			(1,152		)
	Combination debt/equity/other funds	6,283			(251		)	—				—			6,283			(251		)
	Real estate securities fund	—			—			8,511				(1,757		)	8,511			(1,757		)
	Total	$	41,748		$	(1,615	)	$	8,511			$	(1,757	)	$	50,259		$	(3,372	)

Property_Plant_And_Equipment

Property, Plant And Equipment	12 Months Ended
	Dec. 31, 2014
Public Utilities, Property, Plant and Equipment [Abstract]
Property, Plant and Equipment	PROPERTY, PLANT AND EQUIPMENT
	The following is a summary of our property, plant and equipment balance.
		As of December 31,
		2014			2013
		(In Thousands)
	Electric plant in service	$	10,620,292		$	9,753,787
	Electric plant acquisition adjustment	802,318			802,318
	Accumulated depreciation	(4,112,483		)	(3,971,735		)
		7,310,127			6,584,370
	Construction work in progress	773,144			904,586
	Nuclear fuel, net	79,637			62,960
	Net property, plant and equipment	$	8,162,908		$	7,551,916
	The following is a summary of property, plant and equipment of VIEs.
		As of December 31,
		2014			2013
		(In Thousands)
	Electric plant of VIEs	$	497,999		$	513,793
	Accumulated depreciation of VIEs	(219,426		)	(217,167		)
	Net property, plant and equipment of VIEs	$	278,573		$	296,626
	We revised our depreciation rates to reflect changes in the estimated useful lives of some of our assets in 2012. We recorded depreciation expense on property, plant and equipment of $263.8 million in 2014, $249.9 million in 2013 and $247.8 million in 2012. Approximately $9.7 million, $9.7 million and $9.8 million of depreciation expense in 2014, 2013 and 2012, respectively, was attributable to property, plant and equipment of VIEs.

Joint_Ownership_of_Utility_Pla

Joint Ownership of Utility Plants	12 Months Ended
	Dec. 31, 2014
Regulated Operations [Abstract]
Joint Ownership of Utility Plants	JOINT OWNERSHIP OF UTILITY PLANTS
	Under joint ownership agreements with other utilities, we have undivided ownership interests in four electric generating stations. Energy generated and operating expenses are divided on the same basis as ownership with each owner reflecting its respective costs in its statements of income and each owner responsible for its own financing. Information relative to our ownership interests in these facilities as of December 31, 2014, is shown in the table below.
	Plant		In-Service	Investment		Accumulated		Construction		Net	Ownership
			Dates			Depreciation		Work in Progress		MW	Percentage
				(Dollars in Thousands)
	La Cygne unit 1 (a)		Jun-73	$	345,866	$	157,550	$	368,445	367	50
	JEC unit 1 (a)		Jul-78	789,142		189,973		11,150		661	92
	JEC unit 2 (a)		May-80	540,871		190,769		3,189		658	92
	JEC unit 3 (a)		May-83	709,497		309,540		3,246		664	92
	Wolf Creek (b)		Sept. 1985	1,818,005		788,602		73,333		549	47
	State Line (c)		Jun-01	100,671		53,347		22		193	40
	Total			$	4,304,052	$	1,689,781	$	459,385	3,092
	_______________
	(a)	Jointly owned with KCPL. Our 8% leasehold interest in Jeffrey Energy Center (JEC) that is consolidated as a VIE is reflected in the net megawatts (MW) and ownership percentage provided above, but not in the other amounts in the table.
	(b)	Jointly owned with KCPL and Kansas Electric Power Cooperative, Inc.
	(c)    Jointly owned with Empire District Electric Company.
	We include in operating expenses on our consolidated statements of income our share of operating expenses of the above plants. Our share of fuel expense for the above plants is generally based on the amount of power we take from the respective plants. Our share of other transactions associated with the plants is included in the appropriate classification on our consolidated financial statements.
	In addition, we also consolidate a VIE that holds our 50% leasehold interest in La Cygne unit 2, which represents 341 MW of net capacity. The VIE's investment in the 50% interest was $392.1 million and accumulated depreciation was $194.5 million as of December 31, 2014. We include these amounts in property, plant and equipment of VIEs, net on our consolidated balance sheets. See Note 17, "Variable Interest Entities," for additional information about VIEs.

ShortTerm_Debt

Short-Term Debt	12 Months Ended
	Dec. 31, 2014
Debt Disclosure [Abstract]
Short-Term Debt	SHORT-TERM DEBT
	In September 2014, Westar Energy extended the term of its $730.0 million revolving credit facility to terminate in September 2018, $81.4 million of which will expire in September 2017. As long as there is no default under the facility, Westar Energy may extend the facility up to an additional two years and may increase the aggregate amount of borrowings under the facility to $1.0 billion, both subject to lender participation. All borrowings under the facility are secured by KGE first mortgage bonds. As of December 31, 2014, no amounts had been borrowed and $15.6 million of letters of credit had been issued under this revolving credit facility. As of December 31, 2013, no amounts had been borrowed and $18.4 million of letters of credit had been issued under this revolving credit facility.
	In 2011, Westar Energy entered into a revolving credit facility with a syndicate of banks for $270.0 million. In February 2014, Westar Energy extended the term of the $270.0 million revolving credit facility to February 2017, of which $20.0 million of this facility will terminate in February 2016. So long as there is no default under the facility, Westar Energy may increase the aggregate amount of borrowings under the facility to $400.0 million, subject to lender participation. All borrowings under the facility are secured by KGE first mortgage bonds. As of December 31, 2014 and 2013, Westar Energy had no borrowed amounts or letters of credit outstanding under this revolving credit facility.
	Westar Energy maintains a commercial paper program pursuant to which it may issue commercial paper up to a maximum aggregate amount outstanding at any one time of $1.0 billion. This program is supported by Westar Energy's revolving credit facilities. Maturities of commercial paper issuances may not exceed 365 days from the date of issuance and proceeds from such issuances will be used to temporarily fund capital expenditures, to redeem debt on an interim basis, for working capital and/or for other general corporate purposes. Westar Energy had $257.6 million and $134.6 million of commercial paper issued and outstanding as of December 31, 2014 and 2013, respectively.
	In addition, total combined borrowings under Westar Energy's commercial paper program and revolving credit facilities may not exceed $1.0 billion at any given time. The weighted average interest rate on short-term borrowings outstanding as of December 31, 2014 and 2013, was 0.52% and 0.28%, respectively. Additional information regarding our short-term debt is as follows.
		As of December 31,
		2014			2013
		(Dollars in Thousands)
	Weighted average short-term debt outstanding during the year	$	232,336		$	228,352
	Weighted daily average interest rates during the year, excluding fees	0.3		%	0.39		%
	Our interest expense on short-term debt was $2.0 million in 2014, $2.4 million in 2013 and $3.2 million in 2012.

LongTerm_Debt

Long-Term Debt	12 Months Ended
	Dec. 31, 2014
Long-term Debt, Unclassified [Abstract]
Long-term Debt	LONG-TERM DEBT
	Outstanding Debt
	The following table summarizes our long-term debt outstanding.
		As of December 31,
		2014			2013
		(In Thousands)
	Westar Energy
	First mortgage bond series:
	6.00% due 2014	$	—		$	250,000
	5.15% due 2017	125,000			125,000
	8.625% due 2018	300,000			300,000
	5.10% due 2020	250,000			250,000
	5.95% due 2035	125,000			125,000
	5.875% due 2036	150,000			150,000
	4.125% due 2042	550,000			550,000
	4.10% due 2043	430,000			250,000
	4.625% due 2043	250,000			250,000
		2,180,000			2,250,000
	Pollution control bond series:
	Variable due 2032, 0.06% as of December 31, 2014; 0.12% as of December 31, 2013	45,000			45,000
	Variable due 2032, 0.08% as of December 31, 2014; 0.12% as of December 31, 2013	30,500			30,500
		75,500			75,500
	KGE
	First mortgage bond series:
	6.70% due 2019	300,000			300,000
	6.15% due 2023	50,000			50,000
	6.53% due 2037	175,000			175,000
	6.64% due 2038	100,000			100,000
	4.30% due 2044	250,000			—
		875,000			625,000
	Pollution control bond series:
	Variable due 2027, 0.08% as of December 31, 2014; 0.10% as of December 31, 2013	21,940			21,940
	5.30% due 2031	—			108,600
	5.30% due 2031	—			18,900
	4.85% due 2031	50,000			50,000
	5.00% due 2031	—			50,000
	Variable due 2032, 0.08% as of December 31, 2014; 0.10% as of December 31, 2013	14,500			14,500
	Variable due 2032, 0.08% as of December 31, 2014; 0.10% as of December 31, 2013	10,000			10,000
		96,440			273,940
	Total long-term debt	3,226,940			3,224,440
	Unamortized debt discount (a)	(11,401		)	(5,482		)
	Long-term debt due within one year	—			(250,000		)
	Long-term debt, net	$	3,215,539		$	2,968,958
	Variable Interest Entities
	6.99% due 2014 (b)	—			316
	5.92% due 2019 (b)	8,413			13,243
	5.647% due 2021 (b)	185,791			208,123
	Total long-term debt of variable interest entities	194,204			221,682
	Unamortized debt premium (a)	294			599
	Long-term debt of variable interest entities due within one year	(27,933		)	(27,479		)
	Long-term debt of variable interest entities, net	$	166,565		$	194,802
	_______________
	(a) We amortize debt discounts and premiums to interest expense over the term of the respective issues.
	(b) Portions of our payments related to this debt reduce the principal balances each year until maturity.
	The Westar Energy and KGE mortgages each contain provisions restricting the amount of first mortgage bonds that could be issued by each entity. We must comply with such restrictions prior to the issuance of additional first mortgage bonds or other secured indebtedness.
	The amount of Westar Energy first mortgage bonds authorized by its Mortgage and Deed of Trust, dated July 1, 1939, as supplemented, is subject to certain limitations as described below. The amount of KGE first mortgage bonds authorized by the KGE Mortgage and Deed of Trust, dated April 1, 1940, as supplemented and amended, is limited to a maximum of $3.5 billion, unless amended further. First mortgage bonds are secured by utility assets. Amounts of additional bonds that may be issued are subject to property, earnings and certain restrictive provisions, except in connection with certain refundings, of each mortgage. As of December 31, 2014, approximately $743.2 million principal amount of additional first mortgage bonds could be issued under the most restrictive provisions in Westar Energy's mortgage. As of December 31, 2014, approximately $1.3 billion principal amount of additional KGE first mortgage bonds could be issued under the most restrictive provisions in KGE's mortgage.
	As of December 31, 2014, we had $121.9 million of variable rate, tax-exempt bonds. While the interest rates for these bonds have been extremely low, we continue to monitor the credit markets and evaluate our options with respect to these bonds.
	In January 2015, Westar Energy redeemed $125.0 million in principal amount of first mortgage bonds bearing stated interest at 5.95% and maturing January 2035.
	In July 2014, KGE issued $250.0 million in principal amount of first mortgage bonds bearing stated interest at 4.30% and maturing July 2044, the proceeds of which were used to retire Westar Energy first mortgage bonds in a principal amount of $250.0 million with a stated interest of 6.00% maturing in July 2014.
	In May 2014, Westar Energy issued $180.0 million in principal amount of first mortgage bonds bearing stated interest at 4.10% and maturing April 2043. These bonds constitute a further issuance of a series of bonds initially issued in March 2013 in a principal amount of $250.0 million. Proceeds from the May 2014 issuance were used in June 2014 to redeem three KGE pollution control bond series totaling $177.5 million principal amount at stated interest rates between 5.00% and 5.30%.
	In August 2013, Westar Energy issued $250.0 million principal amount of first mortgage bonds bearing stated interest at 4.625% and maturing September 2043.
	In June 2013, KGE redeemed two pollution control bond series with a principal amount of $100.0 million and stated interest rates at 5.60% and 6.00%.
	In March 2013, Westar Energy issued $250.0 million principal amount of first mortgage bonds bearing stated interest at 4.10% and maturing April 2043.
	Proceeds from issuances were used to repay short-term debt, which was used to purchase capital equipment, to redeem bonds and for working capital and general corporate purposes.
Maturities
The principal amounts of our long-term debt maturities as of December 31, 2014, are as follows.
Year		Long-term debt			Long-term
					debt of  VIEs
		(In Thousands)
2015		$	—		$	27,933
2016		—			28,309
2017		125,000			26,842
2018		300,000			28,538
2019		300,000			31,485
Thereafter		2,501,940			51,097
Total maturities		$	3,226,940		$	194,204
Interest expense on long-term debt was $158.8 million in 2014, $154.9 million in 2013 and $145.6 million in 2012. Interest expense on long-term debt of VIEs was $11.4 million in 2014, $13.0 million in 2013 and $15.1 million in 2012.

Taxes

Taxes	12 Months Ended
	Dec. 31, 2014
Income Tax Disclosure [Abstract]
Taxes	TAXES
	Income tax expense is comprised of the following components.
		Year Ended December 31,
		2014				2013				2012
		(In Thousands)
	Income Tax Expense (Benefit):
	Current income taxes:
	Federal	$	416			$	135			$	(691	)
	State	(597		)		279				579
	Deferred income taxes:
	Federal	124,923				102,030				102,960
	State	29,657				24,443				26,300
	Investment tax credit amortization	(3,129		)		(3,166		)		(3,012		)
	Income tax expense	$	151,270			$	123,721			$	126,136
	Deferred tax assets and liabilities are reflected on our consolidated balance sheets as follows.
		As of December 31,
		2014				2013
		(In Thousands)
	Current deferred tax assets	$	29,636			$	37,954
	Non-current deferred tax liabilities	1,475,487				1,363,148
	Net deferred tax liabilities	$	1,445,851			$	1,325,194
	The tax effect of the temporary differences and carryforwards that comprise our deferred tax assets and deferred tax liabilities are summarized in the following table.
		As of December 31,
		2014				2013
		(In Thousands)
	Deferred tax assets:
	Tax credit carryforward (a)	$	257,827			$	212,635
	Net operating loss carryforward (b)	179,285				108,885
	Deferred employee benefit costs	158,102				85,720
	Deferred state income taxes	66,557				57,243
	Deferred regulatory gain on sale-leaseback	35,706				38,124
	Deferred compensation	29,315				30,022
	Alternative minimum tax carryforward (c)	24,114				35,666
	Accrued liabilities	23,048				17,396
	Disallowed costs	10,829				11,453
	LaCygne dismantling cost	9,064				8,110
	Capital loss carryforward (d)	1,981				3,447
	Other	27,689				20,058
	Total gross deferred tax assets	823,517				628,759
	Less: Valuation allowance (e)	1,981				3,504
	Deferred tax assets	$	821,536			$	625,255
	Deferred tax liabilities:
	Accelerated depreciation	$	1,664,367			$	1,390,669
	Acquisition premium	163,894				171,907
	Deferred employee benefit costs	158,102				85,720
	Amounts due from customers for future income taxes, net	153,984				163,742
	Deferred state income taxes	59,170				51,504
	Debt reacquisition costs	20,102				19,985
	Storm costs	15,713				21,165
	Pension expense tracker	14,187				21,230
	Other	17,868				24,527
	Total deferred tax liabilities	$	2,267,387			$	1,950,449
	Net deferred tax liabilities	$	1,445,851			$	1,325,194
	_______________
	(a)	Based on filed tax returns and amounts expected to be reported in current year tax returns (December 31, 2014), we had available federal general business tax credits of $73.5 million and state investment tax credits of $184.3 million. The federal general business tax credits were primarily generated from production tax credits. These tax credits expire beginning in 2020 and ending in 2034. The state investment tax credits expire beginning in 2017 and ending in 2030.
	(b)	As of December 31, 2014, we had a federal net operating loss carryforward of $452.8 million, which is available to offset federal taxable income. The net operating losses will expire beginning in 2031 and ending in 2034.
	(c)	As of December 31, 2014, we had available an alternative minimum tax credit carryforward of $24.1 million, which has an unlimited carryforward period.
	(d)	As of December 31, 2014, we had an unused capital loss carryforward of $5.0 million that is available to offset future capital gains. The capital losses will expire in 2016.
	(e)	As we do not expect to realize any significant capital gains in the future, we have established a valuation allowance of $2.0 million. The total valuation allowance related to the deferred tax assets was $2.0 million as of December 31, 2014, and $3.5 million as of December 31, 2013.
	In accordance with various orders, we have reduced our prices to reflect the income tax benefits associated with certain accelerated income tax deductions. We believe it is probable that the net future increases in income taxes payable will be recovered from customers when these temporary income tax benefits reverse. We have recorded a regulatory asset for these amounts. We also have recorded a regulatory liability for our obligation to reduce the prices charged to customers for deferred income taxes recovered from customers at corporate income tax rates higher than current income tax rates. The price reduction will occur as the temporary differences resulting in the excess deferred income tax liabilities reverse. The income tax-related regulatory assets and liabilities as well as unamortized investment tax credits are also temporary differences for which deferred income taxes have been provided. The net deferred income tax liability related to these temporary differences is classified above as amounts due from customers for future income taxes, net.
	Our effective income tax rates are computed by dividing total federal and state income taxes by the sum of such taxes and net income. The difference between the effective income tax rates and the federal statutory income tax rates are as follows.
		Year Ended December 31,
		2014			2013			2012
	Statutory federal income tax rate	35	%		35	%		35	%
Effect of:
State income taxes	4			3.8			4.3
Corporate-owned life insurance policies	(4.0	)		(5.4	)		(4.9	)
Production tax credits	(2.1	)		(2.3	)		(2.4	)
Flow through depreciation for plant-related differences	2			2.2			1.4
AFUDC equity	(1.3	)		(1.2	)		(1.0	)
Amortization of federal investment tax credits	(0.7	)		(0.7	)		(0.7	)
Capital loss utilization carryforward	(0.3	)		(1.1	)		(0.3	)
Liability for unrecognized income tax benefits	(0.2	)		0.1			0.2
Other	(0.5	)		(1.3	)		(0.7	)
Effective income tax rate	31.9	%		29.1	%		30.9	%
We file income tax returns in the U.S. federal jurisdiction as well as various state and foreign jurisdictions. The income tax returns we file will likely be audited by the Internal Revenue Service (IRS) or other tax authorities. With few exceptions, the statute of limitations with respect to U.S. federal, state and local, or non-U.S. income tax examinations by tax authorities remains open for tax year 2011 and forward.
Effective January 1, 2014, we adopted new regulations released by the IRS and United States Treasury Department regarding the deduction and capitalization of expenditures related to tangible property, including the tax treatment of, among other things, materials and supplies and the determination of whether expenditures with respect to tangible property are a deductible repair or must be capitalized, and regulations regarding dispositions of property under the Modified Accelerated Cost Recovery System. The adoption of these regulations did not have a material impact on our consolidated financial results.
Additionally, also effective January 1, 2014, we implemented new FASB accounting guidance regarding the presentation of an unrecognized tax benefit. An unrecognized tax benefit should be presented in the financial statements as a reduction to a deferred tax asset for a net operating loss carryforward, similar tax loss, or a tax credit carryforward. To the extent such tax assets are not available to settle any additional income taxes that would result from the disallowance of a tax position at the reporting date, the unrecognized tax benefit should be presented in the financial statements as a liability and should not be combined with deferred tax assets. We adopted this guidance with retrospective application to prior periods and it did not have a material impact on our consolidated financial statements.
The unrecognized income tax benefits increased from $1.7 million at December 31, 2013, to $3.2 million at December 31, 2014. The increase for unrecognized income tax benefits was largely attributable to tax positions taken with respect to research and experimental tax credits. We do not expect significant changes in the unrecognized income tax benefits in the next 12 months. A reconciliation of the beginning and ending amounts of unrecognized income tax benefits is as follows:
	2014				2013				2012
	(In Thousands)
Unrecognized income tax benefits as of January 1	$	1,703			$	1,219			$	2,483
Additions based on tax positions related to the current year	872				224				373
Additions for tax positions of prior years	813				325				—
Reductions for tax positions of prior years	(200		)		(65		)		(1,637		)
Settlements	—				—				—
Unrecognized income tax benefits as of December 31	$	3,188			$	1,703			$	1,219
The amounts of unrecognized income tax benefits that, if recognized, would favorably impact our effective income tax rate, were $3.2 million, $2.4 million and $2.0 million (net of tax) as of December 31, 2014, 2013 and 2012, respectively.
Interest related to income tax uncertainties is classified as interest expense and accrued interest liability. As of December 31, 2014, we had no amounts accrued for interest related to unrecognized income tax benefits, compared to $0.2 million as of December 31, 2013. We accrued no penalties at either December 31, 2014 or 2013.
As of December 31, 2014 and 2013, we had recorded $1.5 million for probable assessments of taxes other than income taxes.

Employee_Benefit_Plans

Employee Benefit Plans	12 Months Ended
	Dec. 31, 2014
Compensation and Retirement Disclosure [Abstract]
Employee Benefit Plans	EMPLOYEE BENEFIT PLANS
	Pension and Post-Retirement Benefit Plans
	We maintain a qualified non-contributory defined benefit pension plan covering substantially all of our employees. For the majority of our employees, pension benefits are based on years of service and an employee's compensation during the 60 highest paid consecutive months out of 120 before retirement. Non-union employees hired after December 31, 2001, and union employees hired after December 31, 2011, are covered by the same defined benefit pension plan; however, their benefits are derived from a cash balance account formula. We also maintain a non-qualified Executive Salary Continuation Plan for the benefit of certain retired executive officers. We have discontinued accruing any future benefits under this non-qualified plan.
	The amount we contribute to our pension plan for future periods is not yet known, however, we expect to fund our pension plan each year at least to a level equal to current year pension expense. We must also meet minimum funding requirements under the Employee Retirement Income Security Act, as amended by the Pension Protection Act. We may contribute additional amounts from time to time as deemed appropriate.
	In addition to providing pension benefits, we provide certain post-retirement health care and life insurance benefits for substantially all retired employees. We accrue and recover in our prices the costs of post-retirement benefits during an employee's years of service. In 2014 and prior years, our retirees were covered under a health insurance policy. In January 2015, we began giving our retirees a fixed annual allowance, which provides them the flexibility to obtain health coverage in the marketplace that is tailored to their needs.
	As a co-owner of Wolf Creek, KGE is indirectly responsible for 47% of the liabilities and expenses associated with the Wolf Creek pension and post-retirement benefit plans. See Note 12, "Wolf Creek Employee Benefit Plans," for information about Wolf Creek's benefit plans.
	The following tables summarize the status of our pension and post-retirement benefit plans.
		Pension Benefits								Post-retirement Benefits
	As of December 31,	2014				2013				2014				2013
		(In Thousands)
	Change in Benefit Obligation:
	Benefit obligation, beginning of year	$	823,780			$	928,708			$	133,061			$	152,564
	Service cost	16,218				21,420				1,381				2,028
	Interest cost	41,600				38,520				6,351				6,007
	Plan participants’ contributions	—				—				4,232				2,961
	Benefits paid	(39,225		)		(36,529		)		(12,184		)		(10,968		)
	Actuarial (gains) losses	188,272				(128,339		)		16,509				(19,531		)
	Amendments	—				—				(7,834		)		—
	Benefit obligation, end of year (a)	$	1,030,645			$	823,780			$	141,516			$	133,061
	Change in Plan Assets:
	Fair value of plan assets, beginning of year	$	609,817			$	547,931			$	121,766			$	106,793
	Actual return on plan assets	61,291				68,151				7,189				17,361
	Employer contributions	26,400				27,500				—				5,318
	Plan participants’ contributions	—				—				4,074				2,830
	Benefits paid	(36,367		)		(33,765		)		(11,680		)		(10,536		)
	Fair value of plan assets, end of year	$	661,141			$	609,817			$	121,349			$	121,766
	Funded status, end of year	$	(369,504	)		$	(213,963	)		$	(20,167	)		$	(11,295	)
	Amounts Recognized in the Balance Sheets Consist of:
	Current liability	$	(2,716	)		$	(2,740	)		$	(246	)		$	(242	)
	Noncurrent liability	(366,788		)		(211,223		)		(19,921		)		(11,053		)
	Net amount recognized	$	(369,504	)		$	(213,963	)		$	(20,167	)		$	(11,295	)
	Amounts Recognized in Regulatory Assets Consist of:
	Net actuarial loss (gain)	$	329,572			$	186,365			$	(2,253	)		$	(18,890	)
	Prior service cost	2,867				3,393				3,585				13,942
	Transition obligation	—				—				—				—
	Net amount recognized	$	332,439			$	189,758			$	1,332			$	(4,948	)
	_______________
	(a)	As of December 31, 2014 and 2013, pension benefits include non-qualified benefit obligations of $29.8 million and $27.0 million, respectively, which are funded by a trust containing assets of $35.5 million and $34.9 million, respectively, classified as trading securities. The assets in the aforementioned trust are not included in the table above. See Notes 4 and 5, "Financial Instruments and Trading Securities" and "Financial Investments," respectively, for additional information regarding these amounts.
		Pension Benefits								Post-retirement Benefits
	As of December 31,	2014				2013				2014				2013
		(Dollars in Thousands)
	Pension Plans With a Projected Benefit Obligation In Excess of Plan Assets:
	Projected benefit obligation	$	1,030,645			$	823,780			$	—			$	—
	Fair value of plan assets	661,141				609,817				—				—
	Pension Plans With an Accumulated Benefit Obligation In Excess of Plan Assets:
	Accumulated benefit obligation	$	914,800			$	732,150			—				—
	Fair value of plan assets	661,141				609,817				—				—
	Post-retirement Plans With an Accumulated Post-retirement Benefit Obligation In Excess of Plan Assets:
	Accumulated post-retirement benefit obligation	—				—				$	141,516			$	133,061
	Fair value of plan assets	—				—				121,349				121,766
	Weighted-Average Actuarial Assumptions used to Determine Net Periodic Benefit Obligation:
	Discount rate	4.17		%		5.07		%		4.1		%		4.88		%
	Compensation rate increase	4		%		4		%		—				—
	We use a measurement date of December 31 for our pension and post-retirement benefit plans. The discount rate used to determine the current year pension obligation and the following year's pension expense is based on a bond selection-settlement portfolio approach. This approach develops a discount rate by selecting a portfolio of high quality, non-callable corporate bonds that generate sufficient cash flow to provide for the projected benefit payments of the plan. After the bond portfolio is selected, a single interest rate is determined that equates the present value of the plan's projected benefit payments discounted at this rate with the market value of the bonds selected. The decrease in the discount rates used as of December 31, 2014, increased the pension and post-retirement benefit obligations by approximately $123.5 million and $11.2 million, respectively.
	We utilize actuarial assumptions about mortality to calculate the pension and post-retirement benefit obligations. In 2014, revised mortality tables were published which reflect improved life expectancies based on past experience and future projections. We adopted the revised mortality tables as of December 31, 2014, resulting in an increase to the pension and post-retirement benefit obligations by approximately $58.6 million and $5.9 million, respectively.
	We amortize prior service cost on a straight-line basis over the average future service of the active employees (plan participants) benefiting under the plan at the time of the amendment. We amortize the net actuarial gain or loss on a straight-line basis over the average future service of active plan participants benefiting under the plan without application of an amortization corridor. The KCC allows us to record a regulatory asset or liability to track the cumulative difference between current year pension and post-retirement benefits expense and the amount of such expense recognized in setting our prices. We accumulate such regulatory asset or liability between general rate reviews and amortize the accumulated amount as part of resetting our base prices. Following is additional information regarding our pension and post-retirement benefit plans.
			Pension Benefits												Post-retirement Benefits
	Year Ended December 31,		2014				2013				2012				2014			2013			2012
			(Dollars in Thousands)
	Components of Net Periodic Cost (Benefit):
	Service cost		$	16,218			$	21,420			$	19,556			$	1,381		$	2,028		$	2,057
	Interest cost		41,600				38,520				39,576				6,351			6,007			6,298
	Expected return on plan assets		(36,438		)		(33,405		)		(32,283		)		(6,576		)	(6,691		)	(5,491		)
	Amortization of unrecognized:
Transition obligation, net		—				—				—				—			325			3,912
Prior service costs		526				601				612				2,524			2,524			2,524
Actuarial loss, net		19,362				33,914				32,778				(742		)	1,125			1,503
Net periodic cost before regulatory adjustment		41,268				61,050				60,239				2,938			5,318			10,803
Regulatory adjustment (a)		15,479				3,693				(6,523		)		4,499			2,922			23
Net periodic cost		$	56,747			$	64,743			$	53,716			$	7,437		$	8,240		$	10,826
Other Changes in Plan Assets and Benefit Obligations Recognized in Regulatory Assets:
Current year actuarial (gain)/loss		$	162,569			$	(163,086	)		$	18,451			$	15,896		$	(30,201	)	$	(4,239	)
Amortization of actuarial (loss)		(19,362		)		(33,914		)		(32,778		)		742			(1,125		)	(1,503		)
Current year prior service cost		—				—				—				(7,834		)	—			—
Amortization of prior service costs		(526		)		(601		)		(612		)		(2,524		)	(2,525		)	(2,524		)
Amortization of transition obligation		—				—				—				—			(325		)	(3,912		)
Total recognized in regulatory assets		$	142,681			$	(197,601	)		$	(14,939	)		$	6,280		$	(34,176	)	$	(12,178	)
Total recognized in net periodic cost and regulatory assets		$	199,428			$	(132,858	)		$	38,777			$	13,717		$	(25,936	)	$	(1,352	)
Weighted-Average Actuarial Assumptions used to Determine Net Periodic Cost (Benefit):
Discount rate		5.07		%		4.13		%		4.5		%		4.88		%	3.99		%	4.25		%
Expected long-term return on plan assets		6.5		%		6.5		%		6.5		%		6		%	6		%	6		%
Compensation rate increase		4		%		4		%		4		%		4		%	4		%	—		%
_______________
(a)	The regulatory adjustment represents the difference between current period pension or post-retirement benefit expense and the amount of such expense recognized in setting our prices.
We estimate that we will amortize the following amounts from regulatory assets into net periodic cost in 2015.
	Pension				Post-retirement
	Benefits				Benefits
	(In Thousands)
Actuarial loss	$	32,131			$	379
Prior service cost	520				455
Total	$	32,651			$	834
We base the expected long-term rate of return on plan assets on historical and projected rates of return for current and planned asset classes in the plans' investment portfolios. We select assumed projected rates of return for each asset class after analyzing long-term historical experience and future expectations of the volatility of the various asset classes. Based on target asset allocations for each asset class, we develop an overall expected rate of return for the portfolios, adjusted for historical and expected experience of active portfolio management results compared to benchmark returns and for the effect of expenses paid from plan assets.
For measurement purposes, the assumed annual health care cost growth rates were as follows.
	As of December 31,
	2014 (a)		2013
Health care cost trend rate assumed for next year	—		7.50%
Rate to which the cost trend rate is assumed to decline (the ultimate trend rate)	—		5.00%
Year that the rate reaches the ultimate trend rate	—		2019
_______________
(a)	Amounts are zero due to a change in our post retirement medical plan, effective January 2015, whereby we began to offer retirees a fixed cost allowance to obtain health coverage.
The health care cost trend rate affects the projected benefit obligation. A 1% change in assumed health care cost growth rates would have effects shown in the following table.
	One-Percentage-				One-Percentage-
	Point Increase				Point Decrease
	(In Thousands)
Effect on total of service and interest cost	$	134			$	(120	)
Effect on post-retirement benefit obligation (a)	—				—
_______________
(a)	Amounts are zero due to a change in our post retirement medical plan, effective January 2015, whereby we began to offer retirees a fixed cost allowance to obtain health coverage.
Plan Assets
We believe we manage pension and post-retirement benefit plan assets in a prudent manner with regard to preserving principal while providing reasonable returns. We have adopted a long-term investment horizon such that the chances and duration of investment losses are weighed against the long-term potential for appreciation of assets. Part of our strategy includes managing interest rate sensitivity of plan assets relative to the associated liabilities. The primary objective of the pension plan is to provide a source of retirement income for its participants and beneficiaries, and the primary financial objective of the plan is to improve its funded status. The primary objective of the post-retirement benefit plan is growth in assets and preservation of principal, while minimizing interim volatility, to meet anticipated claims of plan participants. We delegate the management of our pension and post-retirement benefit plan assets to independent investment advisors who hire and dismiss investment managers based upon various factors. The investment advisors are instructed to diversify investments across asset classes, sectors and manager styles to minimize the risk of large losses, based upon objectives and risk tolerance specified by management, which include allowable and/or prohibited investment types. We measure and monitor investment risk on an ongoing basis through quarterly investment portfolio reviews and annual liability measurements.
We have established certain prohibited investments for our pension and post-retirement benefit plans. Such prohibited investments include loans to the company or its officers and directors as well as investments in the company's debt or equity securities, except as may occur indirectly through investments in diversified mutual funds. In addition, to reduce concentration of risk, the pension plan will not invest in any fund that holds more than 25% of its total assets to be invested in the securities of one or more issuers conducting their principal business activities in the same industry. This restriction does not apply to investments in securities issued or guaranteed by the U.S. government or its agencies.
Target allocations for our pension plan assets are approximately 39% to debt securities, 39% to equity securities, 12% to alternative investments such as real estate securities, hedge funds and private equity investments, and the remaining 10% to a fund which provides tactical portfolio overlay by investing in debt and equity securities. Our investments in equity include investment funds with underlying investments in domestic and foreign large-, mid- and small-cap companies, derivatives related to such holdings, private equity investments including late-stage venture investments and other investments. Our investments in debt include core and high-yield bonds. Core bonds are comprised of investment funds with underlying investments in investment grade debt securities of corporate entities, obligations of U.S. and foreign governments and their agencies and other debt securities. High-yield bonds include investment funds with underlying investments in non-investment grade debt securities of corporate entities, obligations of foreign governments and their agencies, private debt securities and other debt securities. Real estate securities consist primarily of funds invested in core real estate throughout the U.S. while alternative funds invest in wide ranging investments including equity and debt securities of domestic and foreign corporations, debt securities issued by U.S. and foreign governments and their agencies, structured debt, warrants, exchange-traded funds, derivative instruments, private investment funds and other investments.
Target allocations for our post-retirement benefit plan assets are 65% to equity securities and 35% to debt securities. Our investments in equity securities include investment funds with underlying investments primarily in domestic and foreign large-, mid- and small-cap companies. Our investments in debt securities include a core bond fund with underlying investments in investment grade debt securities of domestic and foreign corporate entities, obligations of U.S. and foreign governments and their agencies, private placement securities and other investments.
Similar to other assets measured at fair value, GAAP establishes a hierarchal framework for disclosing the transparency of the inputs utilized in measuring pension and post-retirement benefit plan assets at fair value. From time to time, the pension and post-retirement benefits trusts may buy and sell investments resulting in changes within the hierarchy. See Note 4, "Financial Instruments and Trading Securities," for a description of the hierarchal framework.
All level 2 pension investments are held in investment funds that are measured at fair value using daily net asset values as reported by the trustee, except for $59.0 million as of December 31, 2014, invested directly in long-term U.S. Treasury securities. We also maintain certain level 3 investments in private equity, alternative investments and real estate securities that are also measured at fair value using net asset value, but require significant unobservable market information to measure the fair value of the underlying investments. The underlying investments in private equity are measured at fair value utilizing both market- and income-based models, public company comparables, investment cost or the value derived from subsequent financings. Adjustments are made when actual performance differs from expected performance; when market, economic or company-specific conditions change; and when other news or events have a material impact on the security. The underlying alternative investments include collateralized debt obligations, mezzanine debt and a variety of other investments. The fair value of these investments is measured using a variety of primarily market-based models utilizing inputs such as security prices, maturity, call features, ratings and other developments related to specific securities. The underlying real estate investments are measured at fair value using a combination of market- and income-based models utilizing market discount rates, projected cash flows and the estimated value into perpetuity.
The following table provides the fair value of our pension plan assets and the corresponding level of hierarchy as of December 31, 2014 and 2013.
As of December 31, 2014		Level 1				Level 2				Level 3				Total
		(In Thousands)
Assets:
Domestic equity funds		$	—			$	160,574			$	23,996			$	184,570
International equity fund		—				82,604				—				82,604
Core bond funds		—				224,740				—				224,740
High-yield bond fund		—				20,412				—				20,412
Emerging market bond fund		—				14,685				—				14,685
Combination debt/equity/other fund		—				61,632				—				61,632
Alternative investment funds		—				—				41,141				41,141
Real estate securities fund		—				—				26,439				26,439
Cash equivalents		—				4,918				—				4,918
Total Assets Measured at Fair Value		$	—			$	569,565			$	91,576			$	661,141
As of December 31, 2013
Assets:
Domestic equity funds		$	—			$	161,272			$	22,488			$	183,760
International equity fund		—				75,872				—				75,872
Core bond funds		—				191,506				—				191,506
High-yield bond fund		—				20,796				—				20,796
Emerging market bond fund		—				13,113				—				13,113
Combination debt/equity/other fund		—				58,336				—				58,336
Alternative investment funds		—				—				39,171				39,171
Real estate securities fund		—				—				24,022				24,022
Cash equivalents		—				3,241				—				3,241
Total Assets Measured at Fair Value		$	—			$	524,136			$	85,681			$	609,817
The following table provides a reconciliation of pension plan assets measured at fair value using significant level 3 inputs for the years ended December 31, 2014 and 2013.
	Domestic				Alternative Investment				Real Estate				Total
	Equity Funds				Funds				Securities Fund
	(In Thousands)
Balance as of December 31, 2013	$	22,488			$	39,171			$	24,022			$	85,681
Actual gain (loss) on plan assets:
Relating to assets still held at the reporting date	(154		)		1,970				2,630				4,446
Relating to assets sold during the period	1,365				—				29				1,394
Purchases, issuances and settlements, net	297				—				(242		)		55
Balance as of December 31, 2014	$	23,996			$	41,141			$	26,439			$	91,576
Balance as of December 31, 2012	$	18,493			$	45,535			$	20,927			$	84,955
Actual gain (loss) on plan assets:
Relating to assets still held at the reporting date	3,845				1,936				3,307				9,088
Relating to assets sold during the period	—				826				—				826
Purchases, issuances and settlements, net	150				(9,126		)		(212		)		(9,188		)
Balance as of December 31, 2013	$	22,488			$	39,171			$	24,022			$	85,681
The following table provides the fair value of our post-retirement benefit plan assets and the corresponding level of hierarchy as of December 31, 2014 and 2013.
As of December 31, 2014		Level 1				Level 2				Level 3				Total
		(In Thousands)
Assets:
Domestic equity funds		$	—			$	63,600			$	—			$	63,600
International equity fund		—				14,783				—				14,783
Core bond funds		—				42,390				—				42,390
Cash equivalents		—				576				—				576
Total Assets Measured at Fair Value		$	—			$	121,349			$	—			$	121,349
As of December 31, 2013
Assets:
Domestic equity funds		$	—			$	64,080			$	—			$	64,080
International equity fund		—				16,018				—				16,018
Core bond funds		—				41,092				—				41,092
Cash equivalents		—				576				—				576
Total Assets Measured at Fair Value		$	—			$	121,766			$	—			$	121,766
Cash Flows
The following table shows the expected cash flows for our pension and post-retirement benefit plans for future years.
Expected Cash Flows		Pension Benefits								Post-retirement Benefits
		To/(From) Trust				(From)				To/(From) Trust				(From)
						Company Assets								Company Assets
		(In Millions)
Expected contributions:
2015		$	42							$	—
Expected benefit payments:
2015		$	(35.1	)		$	(2.8	)		$	(8.2	)		$	(0.2	)
2016		(37.3		)		(2.8		)		(8.3		)		(0.2		)
2017		(39.5		)		(2.8		)		(8.4		)		(0.2		)
2018		(41.9		)		(2.7		)		(8.6		)		(0.2		)
2019		(44.2		)		(2.7		)		(8.7		)		(0.2		)
2020-2024		(257.8		)		(13.0		)		(43.5		)		(1.0		)
Savings Plans
We maintain a qualified 401(k) savings plan in which most of our employees participate. We match employees' contributions in cash up to specified maximum limits. Our contributions to the plan are deposited with a trustee and invested at the direction of plan participants into one or more of the investment alternatives we provide under the plan. Our contributions totaled $7.0 million in 2014, $6.9 million in 2013 and $7.1 million in 2012.
Stock-Based Compensation Plans
We have a long-term incentive and share award plan (LTISA Plan), which is a stock-based compensation plan in which employees and directors are eligible for awards. The LTISA Plan was implemented as a means to attract, retain and motivate employees and directors. Under the LTISA Plan, we may grant awards in the form of stock options, dividend equivalents, share appreciation rights, RSUs, performance shares and performance share units to plan participants. Up to 8.25 million shares of common stock may be granted under the LTISA Plan. As of December 31, 2014, awards of approximately 5.0 million shares of common stock had been made under the plan.
All stock-based compensation is measured at the grant date based on the fair value of the award and is recognized as an expense in the consolidated statement of income over the requisite service period. The requisite service periods range from one to ten years. The table below shows compensation expense and income tax benefits related to stock-based compensation arrangements that are included in our net income.
	Year Ended December 31,
	2014				2013				2012
	(In Thousands)
Compensation expense	$	7,193			$	8,121			$	7,203
Income tax benefits related to stock-based compensation arrangements	2,845				3,212				2,849
We use RSU awards for our stock-based compensation awards. RSU awards are grants that entitle the holder to receive shares of common stock as the awards vest. These RSU awards are defined as nonvested shares and do not include restrictions once the awards have vested.
RSU awards with only service requirements vest solely upon the passage of time. We measure the fair value of these RSU awards based on the market price of the underlying common stock as of the grant date. RSU awards with only service conditions that have a graded vesting schedule are recognized as an expense in the consolidated statement of income on a straight-line basis over the requisite service period for the entire award. Nonforfeitable dividend equivalents, or the rights to receive cash equal to the value of dividends paid on Westar Energy's common stock, are paid on these RSUs during the vesting period.
RSU awards with performance measures vest upon expiration of the award term. The number of shares of common stock awarded upon vesting will vary from 0% to 200% of the RSU award, with performance tied to our total shareholder return relative to the total shareholder return of our peer group. We measure the fair value of these RSU awards using a Monte Carlo simulation technique that uses the closing stock price at the valuation date and incorporates assumptions for inputs of the expected volatility and risk-free interest rates. Expected volatility is based on historical volatility over three years using daily stock price observations. The risk-free interest rate is based on treasury constant maturity yields as reported by the Federal Reserve and the length of the performance period. For the 2014 valuation, inputs for expected volatility ranged from 15.2% to 23.3% and the risk-free interest rate was approximately 0.3%. For the 2013 valuation, inputs for expected volatility ranged from 15.0% to 23.5% and the risk-free interest rate was approximately 0.3%. For these RSU awards, dividend equivalents accumulate over the vesting period and are paid in cash based on the number of shares of common stock awarded upon vesting.
During the years ended December 31, 2014, 2013 and 2012, our RSU activity for awards with only service requirements was as follows.
	As of December 31,
	2014							2013							2012
	Shares			Weighted-				Shares			Weighted-				Shares		Weighted-
				Average							Average						Average
				Grant Date							Grant Date						Grant Date
				Fair Value							Fair Value						Fair Value
	(Shares In Thousands)
Nonvested balance, beginning of year	352.5			$	28.38			351.1			$	25.47			368.5		$	23.83
Granted	131.5			34.53				139.6			31.06				131		27.82
Vested	(118.2	)		26.19				(125.5	)		23.22				(127.8	)	23.34
Forfeited	(23.6	)		30				(12.7	)		28.35				(20.6	)	24.4
Nonvested balance, end of year	342.2			31.38				352.5			28.38				351.1		25.47
Total unrecognized compensation cost related to RSU awards with only service requirements was $4.4 million and $4.4 million as of December 31, 2014 and 2013, respectively. We expect to recognize these costs over a remaining weighted-average period of 1.9 years. The total fair value of RSUs with only service requirements that vested during the years ended December 31, 2014, 2013 and 2012, was $3.9 million, $3.7 million and $3.7 million, respectively.
During the years ended December 31, 2014, 2013 and 2012, our RSU activity for awards with performance measures was as follows.
	As of December 31,
	2014							2013							2012
	Shares			Weighted-				Shares			Weighted-				Shares		Weighted-
				Average							Average						Average
				Grant Date							Grant Date						Grant Date
				Fair Value							Fair Value						Fair Value
	(Shares In Thousands)
Nonvested balance, beginning of year	350.1			$	30.35			340.1			$	29.2			324.2		$	28.31
Granted	126.1			35.97				134.4			31.54				122.3		28.84
Vested	(108.2	)		30.56				(112.5	)		28.29				(88.2	)	25.46
Forfeited	(22.9	)		30.7				(11.9	)		30.45				(18.2	)	29
Nonvested balance, end of year	345.1			32.31				350.1			30.35				340.1		29.2
As of December 31, 2014 and 2013, total unrecognized compensation cost related to RSU awards with performance measures was $3.8 million and $4.0 million, respectively. We expect to recognize these costs over a remaining weighted-average period of 1.7 years. The total fair value of RSUs with performance measures that vested during the years ended December 31, 2014, 2013 and 2012, was $0.5 million, $2.3 million and $3.6 million, respectively.
Another component of the LTISA Plan is the Executive Stock for Compensation program under which, in the past, eligible employees were entitled to receive deferred common stock in lieu of current cash compensation. Although this plan was discontinued in 2001, dividends will continue to be paid to plan participants on their outstanding plan balance until distribution. Plan participants were awarded 403 shares of common stock for dividends in 2014, 551 shares in 2013 and 666 shares in 2012. Participants received common stock distributions of 1,944 shares in 2014, 3,456 shares in 2013 and 1,461 shares in 2012.
Income tax benefits resulting from income tax deductions in excess of the related compensation cost recognized in the financial statements is classified as cash flows from financing activities in the consolidated statements of cash flows.

Wolf_Creek_Employee_Benefit_Pl

Wolf Creek Employee Benefit Plans	12 Months Ended
	Dec. 31, 2014
Defined Benefit Pension Plans and Defined Benefit Postretirement Plans Disclosure [Abstract]
Wolf Creek Employee Benefit Plans	WOLF CREEK EMPLOYEE BENEFIT PLANS
	Pension and Post-retirement Benefit Plans
	As a co-owner of Wolf Creek, KGE is indirectly responsible for 47% of the liabilities and expenses associated with the Wolf Creek pension and post-retirement benefit plans. KGE accrues its 47% share of Wolf Creek's cost of pension and post-retirement benefits during the years an employee provides service. The following tables summarize the status of KGE's 47% share of the Wolf Creek pension and post-retirement benefit plans.
		Pension Benefits								Post-retirement Benefits
	As of December 31,	2014				2013				2014				2013
		(In Thousands)
	Change in Benefit Obligation:
	Benefit obligation, beginning of year	$	162,820			$	176,891			$	10,010			$	11,020
	Service cost	5,695				6,835				173				206
	Interest cost	8,469				7,562				464				413
	Plan participants’ contributions	—				—				766				696
	Benefits paid	(5,039		)		(4,349		)		(1,292		)		(1,022		)
	Actuarial (gains) losses	38,375				(24,119		)		(1,881		)		(1,303		)
	Benefit obligation, end of year	$	210,320			$	162,820			$	8,240			$	10,010
	Change in Plan Assets:
	Fair value of plan assets, beginning of year	$	114,734			$	98,051			$	17			$	13
	Actual return on plan assets	7,626				13,166				—				—
	Employer contributions	7,089				7,624				515				330
	Plan participants' contributions	—				—				766				696
	Benefits paid	(4,789		)		(4,107		)		(1,292		)		(1,022		)
	Fair value of plan assets, end of year	$	124,660			$	114,734			$	6			$	17
	Funded status, end of year	$	(85,660	)		$	(48,086	)		$	(8,234	)		$	(9,993	)
	Amounts Recognized in the Balance Sheets Consist of:
	Current liability	$	(247	)		$	(237	)		$	(575	)		$	(614	)
	Noncurrent liability	(85,413		)		(47,849		)		(7,659		)		(9,379		)
	Net amount recognized	$	(85,660	)		$	(48,086	)		$	(8,234	)		$	(9,993	)
	Amounts Recognized in Regulatory Assets Consist of:
	Net actuarial loss	$	65,049			$	29,203			$	29			$	2,076
	Prior service cost	559				617				—				—
	Net amount recognized	$	65,608			$	29,820			$	29			$	2,076
		Pension Benefits								Post-retirement Benefits
	As of December 31,	2014				2013				2014				2013
		(Dollars in Thousands)
	Pension Plans With a Projected Benefit Obligation In Excess of Plan Assets:
	Projected benefit obligation	$	210,320			$	162,820			$	—			$	—
	Fair value of plan assets	124,660				114,734				—				—
	Pension Plans With an Accumulated Benefit Obligation In Excess of Plan Assets:
	Accumulated benefit obligation	$	179,228			$	137,459			$	—			$	—
	Fair value of plan assets	124,660				114,734				—				—
	Post-retirement Plans With an Accumulated Post-retirement Benefit Obligation In Excess of Plan Assets:
	Accumulated post-retirement benefit obligation	$	—			$	—			$	8,240			$	10,010
	Fair value of plan assets	—				—				6				16
	Weighted-Average Actuarial Assumptions used to Determine Net Periodic Benefit Obligation:
	Discount rate	4.2		%		5.11		%		3.89		%		4.7		%
	Compensation rate increase	4		%		4		%		—				—
	Wolf Creek uses a measurement date of December 31 for its pension and post-retirement benefit plans. The discount rate used to determine the current year pension obligation and the following year's pension expense is based on a bond selection-settlement portfolio approach. This approach develops a discount rate by selecting a portfolio of high quality, non-callable corporate bonds that generate sufficient cash flow to provide for the projected benefit payments of the plan. After the bond portfolio is selected, a single interest rate is determined that equates the present value of the plan's projected benefit payments discounted at this rate with the market value of the bonds selected. The decrease in the discount rates used as of December 31, 2014, increased Wolf Creek's pension and post-retirement benefit obligations by approximately $26.9 million and $0.6 million, respectively.
	Wolf Creek utilizes actuarial assumptions about mortality to calculate the pension and post-retirement benefit obligations. In 2014, revised mortality tables were published which reflect improved life expectancies based on past experience and future projections. Wolf Creek adopted the revised mortality tables as of December 31, 2014, resulting in an increase to the pension and post-retirement benefit obligations by approximately $11.3 million and $0.2 million, respectively.
	The prior service cost (benefit) is amortized on a straight-line basis over the average future service of the active employees (plan participants) benefiting under the plan at the time of the amendment. The net actuarial gain or loss is amortized on a straight-line basis over the average future service of active plan participants benefiting under the plan without application of an amortization corridor. Following is additional information regarding KGE's 47% share of the Wolf Creek pension and other post-retirement benefit plans.
		Pension Benefits												Post-retirement Benefits
	Year Ended December 31,	2014				2013				2012				2014			2013			2012
		(Dollars in Thousands)
	Components of Net Periodic Cost (Benefit):
	Service cost	$	5,695			$	6,835			$	6,062			$	173		$	206		$	191
	Interest cost	8,469				7,562				7,537				464			413			411
	Expected return on plan assets	(8,084		)		(7,373		)		(6,577		)		—			—			—
	Amortization of unrecognized:
	Transition obligation, net	—				—				—				—			—			57
	Prior service costs	58				58				6				—			—			—
	Actuarial loss, net	2,987				5,421				5,366				165			265			234
	Net periodic cost before regulatory adjustment	9,125				12,503				12,394				802			884			893
	Regulatory adjustment (a)	2,328				(641		)		(1,776		)		—			—			—
	Net periodic cost	$	11,453			$	11,862			$	10,618			$	802		$	884		$	893
	Other Changes in Plan Assets and Benefit Obligations Recognized in Regulatory Assets:
	Current year actuarial (gain) loss	$	38,833			$	(29,911	)		$	4,629			$	(1,881	)	$	(1,303	)	$	669
Amortization of actuarial loss (gain)	(2,987		)		(5,421		)		(5,366		)		(165		)	(265		)	(234		)
Current year prior service cost	—				—				650				—			—			—
Amortization of prior service cost	(58		)		(58		)		(6		)		—			—			—
Amortization of transition obligation	—				—				—				—			—			(57		)
Total recognized in regulatory assets	$	35,788			$	(35,390	)		$	(93	)		$	(2,046	)	$	(1,568	)	$	378
Total recognized in net periodic cost and regulatory assets	$	47,241			$	(23,528	)		$	10,525			$	(1,244	)	$	(684	)	$	1,271
Weighted-Average Actuarial Assumptions used to Determine Net Periodic Cost:
Discount rate	5.11		%		4.16		%		4.55		%		4.7		%	3.78		%	4.1		%
Expected long-term return on plan assets	7.5		%		7.5		%		7.5		%		—			—			—
Compensation rate increase	4		%		4		%		4		%		—			—			—
_______________
(a)	The regulatory adjustment represents the difference between current period pension or post-retirement benefit expense and the amount of such expense recognized in setting our prices.
We estimate that we will amortize the following amounts from regulatory assets into net periodic cost in 2015.
	Pension				Post-retirement
	Benefits				Benefits
	(In Thousands)
Actuarial loss	$	5,930			$	2
Prior service cost	57				—
Total	$	5,987			$	2
The expected long-term rate of return on plan assets is based on historical and projected rates of return for current and planned asset classes in the plans' investment portfolios. Assumed projected rates of return for each asset class were selected after analyzing long-term historical experience and future expectations of the volatility of the various asset classes. Based on target asset allocations for each asset class, the overall expected rate of return for the portfolios was developed, adjusted for historical and expected experience of active portfolio management results compared to benchmark returns and for the effect of expenses paid from plan assets.
For measurement purposes, the assumed annual health care cost growth rates were as follows.
	As of December 31,
	2014			2013
Health care cost trend rate assumed for next year	7	%		7.5	%
Rate to which the cost trend rate is assumed to decline (the ultimate trend rate)	5	%		5	%
Year that the rate reaches the ultimate trend rate	2019			2019
The health care cost trend rate affects the projected benefit obligation. A 1% change in assumed health care cost growth rates would have effects shown in the following table.
	One-Percentage-				One-Percentage-
	Point Increase				Point Decrease
	(In Thousands)
Effect on total of service and interest cost	$	(8	)		$	8
Effect on post-retirement benefit obligation	(111		)		113
Plan Assets
Wolf Creek's pension and post-retirement plan investment strategy is to manage assets in a prudent manner with regard to preserving principal while providing reasonable returns. It has adopted a long-term investment horizon such that the chances and duration of investment losses are weighed against the long-term potential for appreciation of assets. Part of its strategy includes managing interest rate sensitivity of plan assets relative to the associated liabilities. The primary objective of the pension plan is to provide a source of retirement income for its participants and beneficiaries, and the primary financial objective of the plan is to improve its funded status. The primary objective of the post-retirement benefit plan is growth in assets and preservation of principal, while minimizing interim volatility, to meet anticipated claims of plan participants. Wolf Creek delegates the management of its pension and post-retirement benefit plan assets to independent investment advisors who hire and dismiss investment managers based upon various factors. The investment advisors are instructed to diversify investments across asset classes, sectors and manager styles to minimize the risk of large losses, based upon objectives and risk tolerance specified by Wolf Creek, which include allowable and/or prohibited investment types. It measures and monitors investment risk on an ongoing basis through quarterly investment portfolio reviews and annual liability measurements.
The target allocations for Wolf Creek's pension plan assets are 31% to international equity securities, 25% to domestic equity securities, 25% to debt securities, 10% to real estate securities, 5% to commodity investments and 4% to other investments. The investments in both international and domestic equity include investments in large-, mid- and small-cap companies, private equity funds and investment funds with underlying investments similar to those previously mentioned. The investments in debt include core and high-yield bonds. Core bonds include funds invested in investment grade debt securities of corporate entities, obligations of U.S. and foreign governments and their agencies and private debt securities. High-yield bonds include a fund with underlying investments in non-investment grade debt securities of corporate entities, private placements and bank debt. Real estate securities include funds invested in commercial and residential real estate properties while commodity investments include funds invested in commodity-related instruments.
All of Wolf Creek's pension plan assets are recorded at fair value using daily net asset values as reported by the trustee. However, level 3 investments in real estate funds and alternative funds are invested in underlying investments that are illiquid and require significant judgment when measuring them at fair value using market- and income-based models. Significant unobservable inputs for underlying real estate investments include estimated market discount rates, projected cash flows and estimated value into perpetuity. Alternative funds invest in a wide range of investments typically with low correlations to traditional investments.
Similar to other assets measured at fair value, GAAP establishes a hierarchal framework for disclosing the transparency of the inputs utilized in measuring pension and post-retirement benefit plan assets at fair value. From time to time, the Wolf Creek pension trust may buy and sell investments resulting in changes within the hierarchy. See Note 4, "Financial Instruments and Trading Securities," for a description of the hierarchal framework.
The following table provides the fair value of KGE's 47% share of Wolf Creek's pension plan assets and the corresponding level of hierarchy as of December 31, 2014 and 2013.
As of December 31, 2014		Level 1				Level 2				Level 3				Total
		(In Thousands)
Assets:
Domestic equity funds		$	—			$	31,580			$	—			$	31,580
International equity funds		—				38,624				—				38,624
Core bond funds		—				31,854				—				31,854
Real estate securities fund		—				6,313				5,649				11,962
Commodities fund		—				5,887				—				5,887
Alternative investment fund		—				—				4,309				4,309
Cash equivalents		—				444				—				444
Total Assets Measured at Fair Value		$	—			$	114,702			$	9,958			$	124,660
As of December 31, 2013
Assets:
Domestic equity funds		$	—			$	30,599			$	—			$	30,599
International equity funds		—				36,868				—				36,868
Core bond funds		—				26,926				—				26,926
Real estate securities fund		—				5,440				5,094				10,534
Commodities fund		—				5,245				—				5,245
Alternative investment fund		—				—				4,147				4,147
Cash equivalents		—				415				—				415
Total Assets Measured at Fair Value		$	—			$	105,493			$	9,241			$	114,734
The following table provides a reconciliation of KGE's 47% share of Wolf Creek's pension plan assets measured at fair value using significant level 3 inputs for the years ended December 31, 2014 and 2013.
	Real Estate				Alternative Investment				Total
	Securities				Fund
	Fund
	(In Thousands)
Balance as of December 31, 2013	$	5,094			$	4,147			$	9,241
Actual gain on plan assets:
Relating to assets still held at the reporting date	555				162				717
Balance as of December 31, 2014	$	5,649			$	4,309			$	9,958
Balance as of December 31, 2012	$	4,541			$	3,900			$	8,441
Actual gain on plan assets:
Relating to assets still held at the reporting date	553				247				800
Balance as of December 31, 2013	$	5,094			$	4,147			$	9,241
Cash Flows
The following table shows our expected cash flows for KGE's 47% share of Wolf Creek's pension and post-retirement benefit plans for future years.
Expected Cash Flows		Pension Benefits								Post-retirement Benefits
		To/(From) Trust				(From)				To/(From) Trust				(From)
						Company Assets								Company Assets
		(In Millions)
Expected contributions:
2015		$	4.7							$	0.6
Expected benefit payments:
2015		$	(5.4	)		$	(0.2	)		$	(0.6	)		$	—
2016		(6.1		)		(0.2		)		(0.6		)		—
2017		(6.8		)		(0.2		)		(0.6		)		—
2018		(7.5		)		(0.2		)		(0.6		)		—
2019		(8.2		)		(0.2		)		(0.7		)		—
2020 - 2024		(51.0		)		(1.1		)		(3.2		)		—
Savings Plan
Wolf Creek maintains a qualified 401(k) savings plan in which most of its employees participate. Wolf Creek matches employees' contributions in cash up to specified maximum limits. Wolf Creek's contributions to the plan are deposited with a trustee and invested at the direction of plan participants into one or more of the investment alternatives provided under the plan. KGE's portion of the expense associated with Wolf Creek's matching contributions was $1.4 million in 2014, $1.4 million in 2013 and $1.3 million in 2012.

Commitments_And_Contingencies

Commitments And Contingencies	12 Months Ended
	Dec. 31, 2014
Commitments and Contingencies Disclosure [Abstract]
Commitments And Contingencies	COMMITMENTS AND CONTINGENCIES
	Purchase Orders and Contracts
	As part of our ongoing operations and capital expenditure program, we have purchase orders and contracts, excluding fuel and transmission, which are discussed below under "—Fuel, Purchased Power and Transmission Commitments." These commitments relate to purchase obligations issued and outstanding at year-end.
	The yearly detail of the aggregate amount of required payments as of December 31, 2014, was as follows.
		Committed
		Amount
		(In Thousands)
	2015	$	406,859
	2016	39,551
	2017	9,223
	Thereafter	27,247
	Total amount committed	$	482,880
	Environmental Matters
	Air Emissions
	We must comply with the federal Clean Air Act, state laws and implementing federal and state regulations that impose, among other things, limitations on emissions generated from our operations, including sulfur dioxide (SO2), particulate matter (PM), nitrogen oxides (NOx), carbon monoxide (CO), mercury and acid gases.
	Emissions from our generating facilities, including PM, SO2 and NOx, have been determined by regulation to reduce visibility by causing or contributing to regional haze. Under federal laws, such as the Clean Air Visibility Rule, and pursuant to an agreement with the Kansas Department of Health and Environment (KDHE) and the Environmental Protection Agency (EPA), we are required to install, operate and maintain controls to reduce emissions found to cause or contribute to regional haze.
	Sulfur Dioxide and Nitrogen Oxide
	Through the combustion of fossil fuels at our generating facilities, we emit SO2 and NOx. Federal and state laws and regulations, including those noted above, and permits issued to us limit the amount of these substances we can emit. If we exceed these limits, we could be subject to fines and penalties. In order to meet SO2 and NOx regulations applicable to our generating facilities, we use low-sulfur coal and natural gas and have equipped the majority of our fossil fuel generating facilities with equipment to control such emissions.
	We are subject to the SO2 allowance and trading program under the federal Clean Air Act Acid Rain Program. Under this program, each unit must have enough allowances to cover its SO2 emissions for that year. In 2014, we had adequate SO2 allowances to meet planned generation and we expect to have enough to cover emissions under this program in 2015.
	Cross-State Air Pollution Rule
	In 2011, the EPA finalized the Cross-State Air Pollution Rule (CSAPR) requiring 28 states, including Kansas, Missouri and Oklahoma, to further reduce emissions of SO2, NOx and fine PM. In April 2014, the U.S. Supreme Court reversed a 2012 decision by the U.S. Court of Appeals for the District of Columbia Circuit that had vacated CSAPR and remanded CSAPR back to the U.S. Court of Appeals for further proceedings consistent with the U.S. Supreme Court decision. In June 2014, the U.S. Department of Justice, on behalf of the EPA, filed a motion to lift the CSAPR stay. In October 2014, the U.S. Court of Appeals granted the motion to lift the CSAPR stay and established a schedule to hear arguments on the remaining outstanding issues beginning in March 2015. During the CSAPR stay, we installed various emission controls at our generation facilities and have projects for additional controls in progress or planned that will reduce the impact of CSAPR. We are unable to determine the full impact of reinstatement of CSAPR until the U.S. Court of Appeals and the EPA take further action, however, we are prepared to comply with CSAPR in its current form.
	National Ambient Air Quality Standards
	Under the federal Clean Air Act, the EPA sets National Ambient Air Quality Standards (NAAQS) for certain emissions considered harmful to public health and the environment, including two classes of PM, NOx (a precursor to ozone), CO and SO2, which result from fossil fuel combustion. Areas meeting the NAAQS are designated attainment areas while those that do not meet the NAAQS are considered nonattainment areas. Each state must develop a plan to bring nonattainment areas into compliance with the NAAQS. NAAQS must be reviewed by the EPA at five-year intervals. KDHE, our state environmental regulatory agency, proposed to designate portions of the Kansas City area nonattainment for the eight-hour ozone standard. The EPA has not acted on KDHE's proposed designation of the Kansas City area and it is uncertain when, or if, such a designation might occur. The Wichita area also exceeded the eight-hour ozone standard and could be designated nonattainment in the future potentially impacting our operations. Nonattainment designations on areas that impact our operations could have a material impact on our consolidated financial results.
	In 2010, the EPA strengthened the NAAQS for both NOx and SO2. We continue to communicate with our regulators regarding these standards and are currently evaluating what impact this could have on our operations and consolidated financial results. If we are required to install additional equipment to control emissions at our facilities, the revised NAAQS could have a material impact on our operations and consolidated financial results.
	In December 2014, the EPA published a proposed rule revising NAAQS for ozone and to make certain other changes, including extending the ozone monitoring season by at least one month. The EPA intends to issue a final rule regarding the ozone NAAQS by October 2015 and make attainment/nonattainment designations for any revised standards by October 2017. We are currently reviewing this proposed new standard and cannot at this time predict the impact it may have on our operations, but it could be material.
	In December 2012, the EPA strengthened an existing NAAQS for one class of PM. In December 2014, the EPA designated the entire state of Kansas as unclassifiable/in attainment with the standard. We cannot at this time predict the impact this designation may have on our operations or consolidated financial results, but it could be material.
	Mercury and Air Toxics Standards
	The operation of power plants results in emissions of mercury, acid gases and other air toxics. In 2012, the EPA's Mercury and Air Toxics Standards (MATS) for power plants became effective, replacing the prior federal Clean Air Mercury Rule and requiring significant reductions in mercury, acid gases and other emissions. Several lawsuits challenging MATS have been filed by other parties and consolidated into a single proceeding before the U.S. Court of Appeals for the District of Columbia Circuit. In April 2014, the U.S. Court of Appeals issued an opinion upholding MATS. In July 2014, numerous states and two trade groups petitioned the U.S. Supreme Court to review this opinion, and in November 2014, the U.S. Supreme Court agreed to such review. The U.S. Supreme Court is expected to rule by June 2015; however, we currently cannot predict the outcome of this litigation, or its impact, if any, on our MATS compliance planning. Nonetheless, we expect to be compliant with the MATS in its current form by April 2016 as currently approved by KDHE. We currently believe that our related investment, based on MATS in its current form, will not be significant.
	Greenhouse Gases
	Byproducts of burning coal and other fossil fuels include carbon dioxide (CO2) and other gases referred to as greenhouse gases (GHGs), which are believed by many to contribute to climate change. The EPA is currently, and has further proposed, using the federal Clean Air Act to limit CO2 and other GHG emissions, and other measures are being imposed or offered by individual states, municipalities and regional agreements with the goal of reducing GHG emissions.
	In January 2014, the EPA re-proposed a New Source Performance Standard that would limit CO2 emissions for new coal and natural gas fueled electric generating units. The re-proposal would limit CO2 emissions to 1,000 lbs per Megawatt hour (MWh) generated for larger natural gas units and 1,100 lbs per MWh generated for smaller natural gas units and coal units. The EPA issued proposed standards addressing CO2 emissions for modified, reconstructed and existing power plants in June 2014. The standards for existing plants is known as the Clean Power Plan. The EPA anticipates issuing final rules for new, modified, reconstructed and existing power plants by summer 2015 and requiring states to submit their implementation state plans to the EPA by no later than summer 2016. The EPA is expected to propose in summer 2015 a federal plan that will implement the Clean Power Plan to be used for states that fail to submit adequate state plans, with such federal plan expected to be finalized by summer 2016. While the Clean Power Plan is not yet final, various legal and judicial challenges to it have been filed. We cannot at this time determine the impact of such proposals on our operations or consolidated financial results, but we believe the costs to comply could be material.
	Under regulations formerly known as the Tailoring Rule, the EPA regulates GHG emissions from certain stationary sources. The regulations are implemented pursuant to two federal Clean Air Act programs, the Prevention of Significant Deterioration (PSD) and Title V Operating Permit Programs, that impose recordkeeping and monitoring requirements and also mandate the implementation of best available control technology (BACT) for projects that cause a significant increase in GHG emissions (currently defined to be more than 75,000 tons or more per year or 100,000 tons or more per year, depending on various factors). In June 2014, the U.S. Supreme Court ruled that the EPA had exceeded its statutory authority in issuing the Tailoring Rule by regulating under the PSD program sources based solely on their GHG emissions. However, the U.S. Supreme Court also held that the EPA could impose GHG BACT requirements for sources already required to implement PSD for other pollutants. Therefore, if future modifications to our sources require PSD review for other pollutants, it may also trigger GHG BACT requirements. The EPA has issued guidance on what BACT entails for the control of GHGs and individual states are now required to determine what controls are required for facilities within their jurisdiction on a case-by-case basis. We cannot at this time determine the impact of these regulations on our future operations or consolidated financial results as the rule has not been finalized, but we believe the cost of compliance with the regulations could be material.
	Water
	We discharge some of the water used in our operations. This water may contain substances deemed to be pollutants. Revised rules governing such discharges from coal-fired power plants are expected to be issued by the EPA by the end of September 2015. Although we cannot at this time determine the timing or impact of compliance with any new regulations, more stringent regulations could have a material impact on our operations or consolidated financial results.
	In October 2014, the EPA’s final standards for cooling intake structures at power plants to protect aquatic life took effect. The standards, based on Section 316(b) of the federal Clean Water Act (CWA), require subject facilities to choose among seven Best Technology Available options to reduce fish impingement. In addition, some facilities must conduct studies to assist permitting authorities to determine whether and what site-specific controls, if any, would be required to reduce entrainment of aquatic organisms. Our current analysis indicates this rule will not have a significant impact on our coal plants that employ cooling towers. Biological monitoring may be required for LaCygne and Wolf Creek. We are currently evaluating the rule's impact on those two plants and cannot predict the resulting impact on our operations or consolidated financial results, but we do not expect it to be material.
	In April 2014, the EPA along with the U.S. Army Corps of Engineers issued a proposed rule defining the Waters of the United States for purposes of the CWA. This rulemaking has the potential to impact all programs under the CWA. Expansion of regulated waterways is possible under the proposal, which could impact several permitting programs. Although we cannot at this time determine the timing or impact of compliance with any new regulations, more stringent regulations could have a material impact on our operations or consolidated financial results.
	Regulation of Coal Combustion Byproducts
	In the course of operating our coal generation plants, we produce coal combustion byproducts (CCBs), including fly ash, gypsum and bottom ash. We recycle some of our ash production, principally by selling to the aggregate industry. In 2010, the EPA proposed a rule to regulate CCB by the federal government. The EPA released a pre-publication version of the rule in December 2014, which we believe will require additional CCB handling, processing and storage equipment and potential closure of certain ash disposal areas, but it has not yet published the final rule. While we cannot at this time estimate the impact and costs associated with future regulations of CCB, we believe the impact on our operations or consolidated financial results could be material.
	Environmental Projects
	We will continue to make significant capital and operating expenditures at our power plants to reduce regulated emissions. The amount of these expenditures could change materially depending on the timing and nature of required investments, the specific outcomes resulting from existing regulations, new regulations, legislation and the manner in which we operate the plants. In addition to the capital investment, in the event we install new equipment, such equipment may cause us to incur significant increases in annual operating and maintenance expense and may reduce the net production, reliability and availability of the plants. The degree to which we will need to reduce emissions and the timing of when such emissions controls may be required is uncertain. Additionally, our ability to access capital markets and the availability of materials, equipment and contractors may affect the timing and ultimate amount of such capital investments.
	We are currently permitted to recover certain of these costs through the ECRR, which, in comparison to a general rate review, reduces the amount of time it takes to begin collecting in retail prices the costs associated with capital expenditures for qualifying environmental improvements. We are not allowed to use the ECRR to collect approximately $610.0 million of the projected capital investment associated with the environmental upgrades at La Cygne. In November 2013, the KCC issued an order allowing us to adjust our prices to include the additional investment in the La Cygne environmental upgrades and to reflect cost reductions elsewhere. The new prices are expected to increase our annual retail revenues by approximately $30.7 million. To change our prices to collect increased operating and maintenance costs, we must file a general rate review with the KCC. We intend to file our next general rate review in March 2015. In addition, the installation of new equipment may cause us to reduce the net production, reliability and availability of our plants. Furthermore, enhancements to our power plants, even if they result in greater efficiency, can trigger a regulatory review, which could result in increased costs or other operational requirements. For additional information regarding our abbreviated rate review, see Note 3, "Rate Matters and Regulation."
	EPA Consent Decree
	As part of a 2010 settlement of a lawsuit filed by the U.S. Department of Justice on behalf of the EPA, we completed installation of selective catalytic reduction equipment on one of our three JEC coal units in December 2014, at a cost of approximately $225.0 million. We also completed installation of less expensive NOx reduction equipment on the other two units to satisfy other terms of the settlement. We plan to recover the costs of installing these systems through our ECRR, but such recovery remains subject to the approval of our regulators.
	Renewable Energy Standard
	Kansas law mandates that we maintain a minimum amount of renewable energy sources. Through 2015, net renewable generation capacity must be 10% of the average peak retail demand for the three prior years, subject to limited exceptions. This requirement increases to 15% for years 2016 through 2019 and 20% for 2020 and thereafter. With our existing wind generation facilities, supply contracts and renewable energy credits, we are able to satisfy the net renewable generation requirement through 2015. With our agreements to purchase an additional 400 MW of installed design capacity from wind generation facilities beginning in 2015 through 2016, we expect to meet the increased requirements for 2020 and thereafter. If we are unable to meet future requirements, our operations and consolidated financial results could be adversely impacted.
	Nuclear Decommissioning
	Nuclear decommissioning is a nuclear industry term for the permanent shutdown of a nuclear power plant and the removal of radioactive components in accordance with Nuclear Regulatory Commission (NRC) requirements. The NRC will terminate a plant's license and release the property for unrestricted use when a company has reduced the residual radioactivity of a nuclear plant to a level mandated by the NRC. The NRC requires companies with nuclear plants to prepare formal financial plans to fund nuclear decommissioning. These plans are designed so that sufficient funds required for nuclear decommissioning will be accumulated prior to the expiration of the license of the related nuclear power plant. Wolf Creek files a nuclear decommissioning site study with the KCC every three years.
	The KCC reviews nuclear decommissioning plans in two phases. Phase one is the approval of the updated nuclear decommissioning study including the estimated costs to decommission the plant. Phase two involves the review and approval of a funding schedule prepared by the owner of the plant detailing how it plans to fund the future-year dollar amount of its pro rata share of the decommissioning costs.
	In 2014, Wolf Creek updated the nuclear decommissioning cost study. Based on the study, our share of decommissioning costs, including decontamination, dismantling and site restoration, is estimated to be approximately $360.0 million. This amount compares to the prior site study estimate of $296.2 million. The site study cost estimate represents the estimate to decommission Wolf Creek as of the site study year. The actual nuclear decommissioning costs may vary from the estimates because of changes in regulations and technologies as well as changes in costs for labor, materials and equipment.
	We are allowed to recover nuclear decommissioning costs in our prices over a period equal to the operating license of Wolf Creek, which is through 2045. The NRC requires that funds sufficient to meet nuclear decommissioning obligations be held in a trust. We believe that the KCC approved funding level will also be sufficient to meet the NRC requirement. Our consolidated financial results would be materially affected if we were not allowed to recover in our prices the full amount of the funding requirement.
	We recovered in our prices and deposited in an external trust fund for nuclear decommissioning approximately $2.8 million in 2014, $2.9 million in 2013 and $3.2 million in 2012. We record our investment in the NDT fund at fair value, which approximated $185.0 million and $175.6 million as of December 31, 2014 and 2013, respectively.
	Storage of Spent Nuclear Fuel
	Under the Nuclear Waste Policy Act of 1982, the Department of Energy (DOE) is responsible for the permanent disposal of spent nuclear fuel. Wolf Creek paid into a federal Nuclear Waste Fund administered by the DOE a quarterly fee for the future disposal of spent nuclear fuel. In November 2013, a federal court of appeals ruled that the DOE must stop collecting this fee effective May 2014. Our share of the fee, calculated as one tenth of a cent for each kilowatt-hour of net nuclear generation delivered to customers, was $0.8 million in 2014, $3.0 million in 2013 and $3.6 million in 2012. We include these costs in fuel and purchased power expense on our consolidated statements of income.
	In 2010, the DOE filed a motion with the NRC to withdraw its then pending application to construct a national repository for the disposal of spent nuclear fuel and high-level radioactive waste at Yucca Mountain, Nevada. An NRC board denied the DOE's motion to withdraw its application and the DOE appealed that decision to the full NRC. In 2011, the NRC issued an evenly split decision on the appeal and also ordered the licensing board to close out its work on the DOE's application by the end of 2011 due to a lack of funding. These agency actions prompted the States of Washington and South Carolina, and a county in South Carolina, to file a lawsuit in a federal Court of Appeals asking the court to compel the NRC to resume its license review and to issue a decision on the license application. In August 2013, the court ordered the NRC to resume its review of the DOE's application. Wolf Creek has an on-site storage facility designed to hold all spent fuel generated at the plant through 2025 and believes it will be able to expand on-site storage as needed past 2025. We cannot predict when, or if, an alternative disposal site will be available to receive Wolf Creek's spent nuclear fuel and will continue to monitor this activity.
	Wolf Creek disposes of most of its low-level radioactive waste at an existing third-party repository in Utah, which we expect will remain available to Wolf Creek. Wolf Creek also contracts with a waste processor to process, take title and dispose in another state most of the remainder of Wolf Creek's low-level radioactive waste. Should on-site waste storage be needed in the future, Wolf Creek has storage capacity on site adequate for approximately four years of plant operations and believes it would be able to expand that storage capacity if needed.
	Nuclear Insurance
	We maintain nuclear liability, property and business interruption insurance for Wolf Creek. These policies contain certain industry standard terms, conditions and exclusions, including, but not limited to, ordinary wear and tear and war. An industry aggregate limit of $3.2 billion plus any reinsurance, indemnity or any other source recoverable by Nuclear Electric Insurance Limited (NEIL), our property and business interruption insurance provider, exists for acts of terrorism affecting Wolf Creek or any other NEIL insured plant within 12 months from the date of the first act. In addition, we may be required to participate in industry-wide retrospective assessment programs as discussed below.
	Nuclear Liability Insurance
	Pursuant to the Price-Anderson Act, which has been reauthorized through December 2025 by the Energy Policy Act of 2005, we are required to insure against public liability claims resulting from nuclear incidents to the current limit of public liability, which is approximately $13.6 billion. This limit of liability consists of the maximum available commercial insurance of $375.0 million and the remaining $13.2 billion is provided through mandatory participation in an industry-wide retrospective assessment program. In addition, Congress could impose additional revenue-raising measures to pay claims. Under this retrospective assessment program, the owners of Wolf Creek are jointly and severally subject to an assessment of up to $127.3 million (our share is $59.8 million), payable at no more than $19.0 million (our share is $8.9 million) per incident per year per reactor. Both the total and yearly assessment is subject to an inflationary adjustment every five years with the next adjustment in 2018.
	Nuclear Property and Business Interruption Insurance
	The owners of Wolf Creek carry decontamination liability, premature nuclear decommissioning liability and property damage insurance for Wolf Creek totaling approximately $2.8 billion. In the event of an accident, insurance proceeds must first be used for reactor stabilization and site decontamination in accordance with a plan mandated by the NRC. Our share of any remaining proceeds can be used to pay for property damage or, if certain requirements are met, including decommissioning the plant, toward a shortfall in the NDT fund. The owners also carry additional insurance with NEIL to cover costs of replacement power and other extra expenses incurred during a prolonged outage resulting from accidental property damage at Wolf Creek. If significant losses were incurred at any of the nuclear plants insured under the NEIL policies, we may be subject to retrospective assessments under the current policies of approximately $39.5 million (our share is $18.6 million).
	Accidental Nuclear Outage Insurance
	Although we maintain various insurance policies to provide coverage for potential losses and liabilities resulting from an accident or an extended outage, our insurance coverage may not be adequate to cover the costs that could result from a catastrophic accident or extended outage at Wolf Creek. Any substantial losses not covered by insurance, to the extent not recoverable in our prices, would have a material effect on our consolidated financial results.
	Fuel, Purchased Power and Transmission Commitments
To supply a portion of the fuel requirements for our power plants, the owners of Wolf Creek have entered into various contracts to obtain nuclear fuel and we have entered into various contracts to obtain coal and natural gas. Some of these contracts contain provisions for price escalation and minimum purchase commitments. As of December 31, 2014, our share of Wolf Creek's nuclear fuel commitments was approximately $27.1 million for uranium concentrates expiring in 2017, $4.1 million for conversion expiring in 2017, $93.3 million for enrichment expiring in 2025 and $33.3 million for fabrication expiring in 2023.
As of December 31, 2014, our coal and coal transportation contract commitments under the remaining terms of the contracts were approximately $1.1 billion. The contracts are for plants that we operate and expire at various times through 2020.
As of December 31, 2014, our natural gas transportation contract commitments under the remaining terms of the contracts were approximately $118.5 million. The natural gas transportation contracts provide firm service to several of our natural gas burning facilities and expire at various times through 2030.
We have power purchase agreements with the owners of six separate wind generation facilities with installed design capacities of 915 MW expiring in 2028 through 2036. Of the 915 MW under contract, 400 MW are associated with agreements pursuant to which generation providers are scheduled to deliver power beginning in 2015 and 2016. Each of the agreements provide for our receipt and purchase of energy produced at a fixed price per unit of output. We estimate that our annual cost of energy purchased from these wind generation facilities will be approximately $68.2 million in 2015 and approximately $110.0 million for the next several years thereafter.
We have acquired rights to transmit a total of 306 MW. Agreements providing transmission capacity for approximately 200 MW expire in 2016 while the remaining 106 MW expire in 2022. As of December 31, 2014, we are committed to spend approximately $34.0 million over the remaining terms of these agreements.

Asset_Retirement_Obligations

Asset Retirement Obligations	12 Months Ended
	Dec. 31, 2014
Asset Retirement Obligation [Abstract]
Asset Retirement Obligations	ASSET RETIREMENT OBLIGATIONS
	Legal Liability
	We have recognized legal obligations associated with the disposal of long-lived assets that result from the acquisition, construction, development or normal operation of such assets. The recording of AROs for regulated operations has no income statement impact due to the deferral of the adjustments through the establishment of a regulatory asset or an offset to a regulatory liability.
	We initially recorded AROs at fair value for the estimated cost to decommission Wolf Creek (KGE's 47% share), dispose of asbestos insulating material at our power plants, remediate ash disposal ponds and dispose of polychlorinated biphenyl (PCB)-contaminated oil.
	The following table summarizes our legal AROs included on our consolidated balance sheets in long-term liabilities.
		As of December 31,
		2014			2013
		(In Thousands)
	Beginning ARO	$	160,682		$	152,648
	Increase in nuclear decommissioning ARO liability	50,683			—
	Increase in other ARO liabilities	9,580			—
	Liabilities settled	(593		)	(973		)
	Accretion expense	10,316			9,007
	Ending ARO	$	230,668		$	160,682
	Wolf Creek filed a nuclear decommissioning cost study with the KCC in 2014. As a result of the study, we recorded a $50.7 million increase in our ARO to reflect revisions to the estimated costs to decommission Wolf Creek.
	Conditional ARO refers to a legal obligation to perform an asset retirement activity in which the timing and/or method of settlement are conditional on a future event that may or may not be within the control of the entity. We determined that our conditional AROs include the retirement of our wind generation facilities, disposal of asbestos insulating material at our power plants, the remediation of ash disposal ponds and the disposal of PCB-contaminated oil.
	We have an obligation to retire our wind generation facilities and remove the foundations. The ARO related to our wind generation facilities was determined based upon the date each wind generation facility was placed into service.
	The amount of the retirement obligation related to asbestos disposal was recorded as of 1990, the date when the EPA published the "National Emission Standards for Hazardous Air Pollutants: Asbestos NESHAP Revision; Final Rule."
	We operate, as permitted by the state of Kansas, ash landfills at several of our power plants. The retirement obligation for the ash landfills was determined based upon the date each landfill was originally placed in service.
	PCB-contaminated oil is contained within company electrical equipment, primarily transformers. The PCB retirement obligation was determined based upon the PCB regulations that originally became effective in 1978.
	Non-Legal Liability - Cost of Removal
	We collect in our prices the costs to dispose of plant assets that do not represent legal retirement obligations. As of December 31, 2014 and 2013, we had $88.2 million and $114.1 million, respectively, in amounts collected, but not yet spent, for removal costs classified as a regulatory liability.

Legal_Proceedings

Legal Proceedings	12 Months Ended
	Dec. 31, 2014
Legal Proceedings [Abstract]
Legal Proceedings	LEGAL PROCEEDINGS
	We and our subsidiaries are involved in various legal, environmental and regulatory proceedings. We believe that adequate provisions have been made and accordingly believe that the ultimate disposition of such matters will not have a material effect on our consolidated financial results. See Note 3, "Rate Matters and Regulation," and Note 13, "Commitments and Contingencies," for additional information.

Common_and_Preferred_Stock

Common and Preferred Stock	12 Months Ended
	Dec. 31, 2014
Common Stock, Number of Shares, Par Value and Other Disclosures [Abstract]
Common and Preferred Stock	COMMON AND PREFERRED STOCK
	Common Stock
	General
	In 2011, Westar Energy shareholders approved an amendment to its Restated Articles of Incorporation to increase the number of shares of common stock authorized to be issued from 150.0 million to 275.0 million. As of December 31, 2014 and 2013, Westar Energy had issued 131.7 million shares and 128.3 million shares, respectively.
	Westar Energy has a direct stock purchase plan (DSPP). Shares of common stock sold pursuant to the DSPP may be either original issue shares or shares purchased in the open market. During 2014 and 2013, Westar Energy issued 0.5 million shares and 0.7 million shares, respectively, through the DSPP and other stock-based plans operated under the LTISA Plan. As of December 31, 2014 and 2013, a total of 1.6 million shares and 2.0 million shares, respectively, were available under the DSPP registration statement.
	Issuances
	In September 2013, Westar Energy entered into two forward sale agreements with two banks. Under the terms of the agreements, the banks, as forward sellers, borrowed 8.0 million shares of Westar Energy's common stock from third parties and sold them to a group of underwriters for $31.15 per share. Pursuant to over-allotment options granted to the underwriters, the underwriters purchased in October 2013 an additional 0.9 million shares from the banks as forward sellers, increasing the total number of shares under the forward sale agreements to approximately 8.9 million. The underwriters received a commission equal to 3.5% of the sales price of all shares sold under each agreement. Westar Energy must settle such transactions within 24 months of the applicable agreement.
	In March 2013, Westar Energy entered into a three-year sales agency financing agreement and master forward sale agreement with a bank. The maximum amount that Westar Energy may offer and sell under the March 2013 master agreements is the lesser of an aggregate of $500.0 million or approximately 25.0 million shares, subject to adjustment for share splits, share combinations and share dividends. Under the terms of the sales agency financing agreement, Westar Energy may offer and sell shares of its common stock from time to time. In addition, under the terms of the sales agency financing agreement and master forward sale confirmation, Westar Energy may from time to time enter into one or more forward sale transactions with the bank, as forward purchaser and the bank will borrow shares of Westar Energy's common stock from third parties and sell them through its agent. The agent receives a commission equal to 1% of the sales price of all shares sold under the agreements. Westar Energy must settle the forward sale transactions within 18 months of the date each transaction is entered.
	In April 2010, Westar Energy entered into a three-year sales agency financing agreement and master forward sale agreement with a bank that was terminated in March 2013. The maximum amount that Westar Energy could offer and sell under the agreements was the lesser of an aggregate of $500.0 million or approximately 22.0 million shares, subject to adjustment for share splits, share combinations and share dividends. Terms under these agreements were generally similar to the March 2013 agreements described above.
	The following table summarizes our common stock activity pursuant to the three forward sale agreements.
		Year Ended December 31,
		2014		2013			2012
	Shares that could be settled at beginning of year	12,052,976		1,753,415			—
	Transactions entered	—		11,367,673			1,753,415
	Transactions settled (a)	2,892,476		1,068,112			—
	Shares that could be settled at end of year (b)	9,160,500		12,052,976			1,753,415
	_______________
	(a) The shares settled during the years ended December 31, 2014 and 2013, were settled with a physical settlement amount of approximately $82.9 million and $27.0 million, respectively.
	(b) Assuming physical share settlement of the 9.2 million shares associated with the forward sale transactions that could be settled as of December 31, 2014, Westar Energy would have received aggregate proceeds of approximately $258.3 million based on a weighted average forward price of $28.20 per share. In February 2015, Westar Energy settled 0.2 million shares with a physical settlement amount of approximately $7.5 million.
	The forward sale transactions are entered into at market prices; therefore, the forward sale agreements have no initial fair value. Westar Energy does not receive any proceeds from the sale of common stock under the forward sale agreements until transactions are settled. Upon settlement, Westar Energy will record the forward sale agreements within equity. Except in specified circumstances or events that would require physical share settlement, Westar Energy is able to elect to settle any forward sale transactions by means of physical share, cash or net share settlement, and is also able to elect to settle the forward sale transactions in whole, or in part, earlier than the stated maturity dates. Currently, Westar Energy anticipates settling the forward sale transactions through physical share settlement. The shares under the forward sale agreements are initially priced when the transactions are entered into and are subject to certain fixed pricing adjustments during the term of the agreements. Accordingly, assuming physical share settlement, Westar Energy's net proceeds from the forward sale transactions will represent the prices established by the forward sale agreements applicable to the time periods in which physical settlement occurs.
	Westar Energy used the proceeds from the transactions described above to repay short-term borrowings, with such borrowed amounts principally used for investments in capital equipment, as well as for working capital and general corporate purposes.
	Preferred Stock Redemption
	In May 2012, Westar Energy provided an irrevocable notice of redemption to holders of all of Westar Energy's preferred shares. Accordingly, we reduced preferred equity to zero, recognized the obligation to redeem the preferred shares as a liability and recognized the redemption premium as a preferred stock dividend. Payment was due to holders of the preferred shares effective July 1, 2012. The table below shows the redemption amounts for all series of preferred stock.
	Rate		Shares		Principal			Call	Premium		Total
					Outstanding			Price			Cost
											to Redeem
	(Dollars in Thousands)
	4.50%		121,613		$	12,161		108.00%	$	973	$	13,134
	4.25%		54,970		5,497			101.50%	82		5,579
	5.00%		37,780		3,778			102.00%	76		3,854
			214,363		$	21,436			$	1,131	$	22,567

Variable_Interest_Entities

Variable Interest Entities	12 Months Ended
	Dec. 31, 2014
Variable Interest Entities [Abstract]
Variable Interest Entities Disclosure [Text Block]	VARIABLE INTEREST ENTITIES
	In determining the primary beneficiary of a VIE, we assess the entity's purpose and design, including the nature of the entity's activities and the risks that the entity was designed to create and pass through to its variable interest holders. A reporting enterprise is deemed to be the primary beneficiary of a VIE if it has (a) the power to direct the activities of the VIE that most significantly impact the VIE's economic performance and (b) the obligation to absorb losses or right to receive benefits from the VIE that could potentially be significant to the VIE. Accounting guidance effective in 2010 requires the primary beneficiary of a VIE to consolidate the VIE. The trusts holding our 8% interest in JEC and our 50% interest in La Cygne unit 2 are VIEs of which we are the primary beneficiary.
	We assess all entities with which we become involved to determine whether such entities are VIEs and, if so, whether or not we are the primary beneficiary of the entities. We also continuously assess whether we are the primary beneficiary of the VIEs with which we are involved. Prospective changes in facts and circumstances may cause us to reconsider our determination as it relates to the identification of the primary beneficiary.
	8% Interest in Jeffrey Energy Center
	Under an agreement that expires in January 2019, we lease an 8% interest in JEC from a trust. The trust was financed with an equity contribution from an owner participant and debt issued by the trust. The trust was created specifically to purchase the 8% interest in JEC and lease it to a third party, and does not hold any other assets. We meet the requirements to be considered the primary beneficiary of the trust. In determining the primary beneficiary of the trust, we concluded that the activities of the trust that most significantly impact its economic performance and that we have the power to direct include (1) the operation and maintenance of the 8% interest in JEC, (2) our ability to exercise a purchase option at the end of the agreement at the lesser of fair value or a fixed amount and (3) our option to require refinancing of the trust's debt. We have the potential to receive benefits from the trust that could potentially be significant if the fair value of the 8% interest in JEC at the end of the agreement is greater than the fixed amount. The possibility of lower interest rates upon refinancing the debt also creates the potential for us to receive significant benefits.
	50% Interest in La Cygne Unit 2
	Under an agreement that expires in September 2029, KGE entered into a sale-leaseback transaction with a trust under which the trust purchased KGE's 50% interest in La Cygne unit 2 and subsequently leased it back to KGE. The trust was financed with an equity contribution from an owner participant and debt issued by the trust. The trust was created specifically to purchase the 50% interest in La Cygne unit 2 and lease it back to KGE, and does not hold any other assets. We meet the requirements to be considered the primary beneficiary of the trust. In determining the primary beneficiary of the trust, we concluded that the activities of the trust that most significantly impact its economic performance and that we have the power to direct include (1) the operation and maintenance of the 50% interest in La Cygne unit 2, (2) our ability to exercise a purchase option at the end of the agreement at the lesser of fair value or a fixed amount and (3) our option to require refinancing of the trust's debt. We have the potential to receive benefits from the trust that could potentially be significant if the fair value of the 50% interest in La Cygne unit 2 at the end of the agreement is greater than the fixed amount. The possibility of lower interest rates upon refinancing the debt also creates the potential for us to receive significant benefits.
	Railcars
	Under two separate agreements, we leased railcars from unrelated trusts to transport coal to some of our power plants. We consolidated the trusts as a VIEs until the agreements expired in May 2013 and November 2014. As a result of deconsolidating the trusts, property, plant and equipment of VIEs, net and noncontrolling interests decreased $14.3 million in 2013 and $7.3 million in 2014.
	Financial Statement Impact
	We have recorded the following assets and liabilities on our consolidated balance sheets related to the VIEs described above.
		As of December 31,
		2014		2013
		(In Thousands)
	Assets:
	Property, plant and equipment of variable interest entities, net	$	278,573	$	296,626
	Regulatory assets (a)	7,882		6,792
	Liabilities:
	Current maturities of long-term debt of variable interest entities	$	27,933	$	27,479
	Accrued interest (b)	2,961		3,472
	Long-term debt of variable interest entities, net	166,565		194,802
	_______________
	(a) Included in long-term regulatory assets on our consolidated balance sheets.
	(b) Included in accrued interest on our consolidated balance sheets.
	All of the liabilities noted in the table above relate to the purchase of the property, plant and equipment. The assets of the VIEs can be used only to settle obligations of the VIEs and the VIEs' debt holders have no recourse to our general credit. We have not provided financial or other support to the VIEs and are not required to provide such support. We did not record any gain or loss upon initial consolidation of the VIEs.

Leases

Leases	12 Months Ended
	Dec. 31, 2014
Leases [Abstract]
Leases	LEASES
	Operating Leases
	We lease office buildings, computer equipment, vehicles, railcars and other property and equipment. These leases have various terms and expiration dates ranging from one to 20 years.
	In determining lease expense, we recognize the effects of scheduled rent increases on a straight-line basis over the minimum lease term. Rental expense and estimated future commitments under operating leases are as follows.
	Year Ended December 31,		Total
			Operating
			Leases
			(In Thousands)
	Rental expense:
	2012		$	17,080
	2013		16,484
	2014		14,143
	Future commitments:
	2015		$	12,396
	2016		10,434
	2017		8,560
	2018		7,148
	2019		5,930
	Thereafter		9,115
	Total future commitments		$	53,583
	Capital Leases
	We identify capital leases based on defined criteria. For both vehicles and computer equipment, new leases are signed each month based on the terms of master lease agreements. The lease term for vehicles is from two to eight years depending on the type of vehicle. Computer equipment has a lease term of three to five years.
	Assets recorded under capital leases are listed below.
		As of December 31,
		2014				2013
		(In Thousands)
	Vehicles	$	18,819			$	12,141
	Computer equipment	1,504				1,758
	Generation plant	40,049				48,346
	Accumulated amortization	(11,741		)		(10,493		)
	Total capital leases	$	48,631			$	51,752
	Capital leases are treated as operating leases for rate making purposes. Minimum annual rental payments, excluding administrative costs such as property taxes, insurance and maintenance, under capital leases are listed below.
	Year Ended December 31,		Total Capital
			Leases
			(In Thousands)
	2015		$	6,379
	2016		5,717
	2017		5,284
	2018		5,131
	2019		4,493
	Thereafter		59,660
			86,664
	Amounts representing imputed interest		(34,922		)
	Present value of net minimum lease payments under capital leases		51,742
	Less: Current portion		3,833
	Total long-term obligation under capital leases		$	47,909

Quarterly_Results_Unaudited

Quarterly Results (Unaudited)	12 Months Ended
	Dec. 31, 2014
Quarterly Financial Information Disclosure [Abstract]
Quarterly Results (Unaudited)	QUARTERLY RESULTS (UNAUDITED)
	Our business is seasonal in nature and, in our opinion, comparisons between the quarters of a year do not give a true indication of overall trends and changes in operations.
	2014	First		Second		Third		Fourth
		(In Thousands, Except Per Share Amounts)
	Revenues (a)	$	628,556	$	612,668	$	764,040	$	596,439
	Net income (a)	70,970		55,822		149,760		45,773
	Net income attributable to Westar Energy, Inc. (a)	68,955		53,473		147,382		43,449
	Per Share Data (a):
	Basic:
	Earnings available	$	0.53	$	0.41	$	1.13	$	0.33
	Diluted:
	Earnings available	$	0.52	$	0.4	$	1.1	$	0.32
	Cash dividend declared per common share	$	0.35	$	0.35	$	0.35	$	0.35
	Market price per common share:
	High	$	35.33	$	38.24	$	38.23	$	43.15
	Low	$	31.67	$	34.51	$	33.76	$	33.73
	_______________
	(a)	Items are computed independently for each of the periods presented and the sum of the quarterly amounts may not equal the total for the year.
	2013	First		Second		Third		Fourth
		(In Thousands, Except Per Share Amounts)
	Revenues (a)	$	546,212	$	569,589	$	694,974	$	559,878
	Net income (a)	53,256		69,451		135,095		43,061
	Net income attributable to Westar Energy, Inc. (a)	51,144		67,188		133,125		41,062
	Per Share Data (a):
	Basic:
	Earnings available	$	0.4	$	0.53	$	1.04	$	0.32
	Diluted:
	Earnings available	$	0.4	$	0.52	$	1.04	$	0.32
	Cash dividend declared per common share	$	0.34	$	0.34	$	0.34	$	0.34
	Market price per common share:
	High	$	33.35	$	34.96	$	34.31	$	32.56
	Low	$	28.59	$	30.13	$	29.79	$	29.95
	_______________
	(a)	Items are computed independently for each of the periods presented and the sum of the quarterly amounts may not equal the total for the year.

Valuation_and_Qualifying_Accou

Valuation and Qualifying Accounts	12 Months Ended
	Dec. 31, 2014
Valuation and Qualifying Accounts [Abstract]
Valuation and Qualifying Accounts	WESTAR ENERGY, INC.
	SCHEDULE II — VALUATION AND QUALIFYING ACCOUNTS
	Description		Balance at		Charged to		Deductions (a)			Balance
			Beginning		Costs  and					at End
			of Period		Expenses					of Period
			(In Thousands)
	Year ended December 31, 2012
	Allowances deducted from assets for doubtful accounts		$	7,384	$	6,617	$	(9,085	)	$	4,916
	Year ended December 31, 2013
	Allowances deducted from assets for doubtful accounts		$	4,916	$	7,039	$	(7,359	)	$	4,596
	Year ended December 31, 2014
	Allowances deducted from assets for doubtful accounts		$	4,596	$	9,752	$	(9,039	)	$	5,309
	_______________
	(a)	Result from write-offs of accounts receivable.

Summary_Of_Significant_Account1

Summary Of Significant Accounting Policies (Policy)	12 Months Ended
	Dec. 31, 2014
Accounting Policies [Abstract]
Principles Of Consolidation	Principles of Consolidation
	We prepare our consolidated financial statements in accordance with generally accepted accounting principles (GAAP) for the United States of America. Our consolidated financial statements include all operating divisions, majority owned subsidiaries and variable interest entities (VIEs) of which we maintain a controlling interest or are the primary beneficiary reported as a single reportable segment. Undivided interests in jointly-owned generation facilities are included on a proportionate basis. Intercompany accounts and transactions have been eliminated in consolidation.
Use Of Management's Estimates	Use of Management's Estimates
	When we prepare our consolidated financial statements, we are required to make estimates and assumptions that affect the reported amounts of assets, liabilities, revenues and expenses, and related disclosure of contingent assets and liabilities, at the date of our consolidated financial statements and the reported amounts of revenues and expenses during the reporting period. We evaluate our estimates on an ongoing basis, including those related to depreciation, unbilled revenue, valuation of investments, forecasted fuel costs included in our retail energy cost adjustment (RECA) billed to customers, income taxes, pension and post-retirement benefits, our asset retirement obligations (AROs) including the decommissioning of Wolf Creek Generating Station (Wolf Creek), environmental issues, VIEs, contingencies and litigation. Actual results may differ from those estimates under different assumptions or conditions.
Regulatory Accounting	Regulatory Accounting
	We apply accounting standards that recognize the economic effects of rate regulation. Accordingly, we have recorded regulatory assets and liabilities when required by a regulatory order or based on regulatory precedent. See Note 3, "Rate Matters and Regulation," for additional information regarding our regulatory assets and liabilities.
Cash And Cash Equivalents	Cash and Cash Equivalents
	We consider investments that are highly liquid and have maturities of three months or less when purchased to be cash equivalents.
Fuel Inventory And Supplies	Fuel Inventory and Supplies
	We state fuel inventory and supplies at average cost.
Property, Plant And Equipment	Property, Plant and Equipment
	We record the value of property, plant and equipment, including that of VIEs, at cost. For plant, cost includes contracted services, direct labor and materials, indirect charges for engineering and supervision and an allowance for funds used during construction (AFUDC). AFUDC represents the allowed cost of capital used to finance utility construction activity. We compute AFUDC by applying a composite rate to qualified construction work in progress. We credit other income (for equity funds) and interest expense (for borrowed funds) for the amount of AFUDC capitalized as construction cost on the accompanying consolidated statements of income as follows:
		Year Ended December 31,
		2014				2013			2012
		(Dollars In Thousands)
	Borrowed funds	$	12,044			$	11,706		$	10,399
	Equity funds	17,029				14,143			11,706
	Total	$	29,073			$	25,849		$	22,105
	Average AFUDC Rates	6.7		%		4.8		%	5		%
	We charge maintenance costs and replacements of minor items of property to expense as incurred, except for maintenance costs incurred for our planned refueling and maintenance outages at Wolf Creek. As authorized by regulators, we defer and amortize to expense ratably over the period between planned outages incremental maintenance costs incurred for such outages. When a unit of depreciable property is retired, we charge to accumulated depreciation the original cost less salvage value.
Allowance For Funds Used During Construction	AFUDC represents the allowed cost of capital used to finance utility construction activity. We compute AFUDC by applying a composite rate to qualified construction work in progress. We credit other income (for equity funds) and interest expense (for borrowed funds) for the amount of AFUDC capitalized as construction cost on the accompanying consolidated statements of income
Depreciation	Depreciation
	We depreciate utility plant using a straight-line method. The depreciation rates are based on an average annual composite basis using group rates that approximated 2.4% in 2014, 2.5% in 2013 and 2.6% in 2012.
	Depreciable lives of property, plant and equipment are as follows.
			Years
	Fossil fuel generating facilities		6	to	78
	Nuclear fuel generating facility		55	to	71
	Wind generating facilities		19	to	20
	Transmission facilities		15	to	75
	Distribution facilities		22	to	68
	Other		5	to	30
Nuclear Fuel	Nuclear Fuel
	We record as property, plant and equipment our share of the cost of nuclear fuel used in the process of refinement, conversion, enrichment and fabrication. We reflect this at original cost and amortize such amounts to fuel expense based on the quantity of heat consumed during the generation of electricity as measured in millions of British thermal units (MMBtu).
Cash Surrender Value of Life Insurance	Cash Surrender Value of Life Insurance
	We recorded on our consolidated balance sheets in other long-term assets the following amounts related to corporate-owned life insurance (COLI) policies.
		As of December 31,
		2014				2013
		(In Thousands)
	Cash surrender value of policies	$	1,306,777			$	1,289,457
	Borrowings against policies	(1,173,956		)		(1,156,341		)
	Corporate-owned life insurance, net	$	132,821			$	133,116
	We record as income increases in cash surrender value and death benefits. We offset against policy income the interest expense that we incur on policy loans. Income from death benefits is highly variable from period to period.
Revenue Recognition	Revenue Recognition
	We record revenue at the time we deliver electricity to customers. We determine the amounts delivered to individual customers through systematic monthly readings of customer meters. At the end of each month, we estimate how much electricity we have delivered since the prior meter reading and record the corresponding unbilled revenue.
	Our unbilled revenue estimate is affected by factors including fluctuations in energy demand, weather, line losses and changes in the composition of customer classes. We recorded estimated unbilled revenue of $61.0 million as of December 31, 2014, and $60.1 million as of December 31, 2013.
Allowance For Doubtful Accounts	Allowance for Doubtful Accounts
	We determine our allowance for doubtful accounts based on the age of our receivables. We charge receivables off when they are deemed uncollectible, which is based on a number of factors including specific facts surrounding an account and management's judgment.
Income Taxes	Income Taxes
	We use the asset and liability method of accounting for income taxes. Under this method, we recognize deferred tax assets and liabilities for the future tax consequences attributable to temporary differences between the financial statement carrying amounts and the tax basis of existing assets and liabilities. We recognize the future tax benefits to the extent that realization of such benefits is more likely than not. We amortize deferred investment tax credits over the lives of the related properties as required by tax laws and regulatory practices. We recognize production tax credits in the year that electricity is generated to the extent that realization of such benefits is more likely than not.
	We record deferred tax assets to the extent capital losses, operating losses, or tax credits will be carried forward to future periods. However, when we believe based on available evidence that we do not, or will not, have sufficient future capital gains or taxable income in the appropriate taxing jurisdiction to realize the entire benefit during the applicable carryforward period, we record a valuation allowance against the deferred tax asset.
	The application of income tax law is complex. Laws and regulations in this area are voluminous and often ambiguous. Accordingly, we must make judgments regarding income tax exposure. Interpretations of and guidance surrounding income tax laws and regulations change over time. As a result, changes in our judgments can materially affect amounts we recognize in our consolidated financial statements. See Note 10, "Taxes," for additional detail on our accounting for income taxes.
Sales Tax	Sales Tax
	We account for the collection and remittance of sales tax on a net basis. As a result, we do not reflect sales tax in our consolidated statements of income.
Earnings Per Share	Earnings Per Share
	We have participating securities in the form of unvested restricted share units (RSUs) with nonforfeitable rights to dividend equivalents that receive dividends on an equal basis with dividends declared on common shares. As a result, we apply the two-class method of computing basic and diluted earnings per share (EPS).
	To compute basic EPS, we divide the earnings allocated to common stock by the weighted average number of common shares outstanding. Diluted EPS includes the effect of potential issuances of common shares resulting from our forward sale agreements and RSUs with forfeitable rights to dividend equivalents. We compute the dilutive effect of potential issuances of common shares using the treasury stock method.
	The following table reconciles our basic and diluted EPS from net income.
		Year Ended December 31,
		2014				2013			2012
		(Dollars In Thousands, Except Per Share Amounts)
	Net income	$	322,325			$	300,863		$	282,462
	Less: Net income attributable to noncontrolling interests	9,066				8,343			7,316
	Net income attributable to Westar Energy, Inc.	313,259				292,520			275,146
	Less: Preferred dividends	—				—			1,616
	Net income allocated to RSUs	790				810			778
	Net income allocated to common stock	$	312,469			$	291,710		$	272,752
	Weighted average equivalent common shares outstanding – basic	130,014,941				127,462,994			126,711,869
	Effect of dilutive securities:
	RSUs	181,397				17,195			97,757
	Forward sale agreements	2,628,187				818,505			89,160
	Weighted average equivalent common shares outstanding – diluted (a)	132,824,525				128,298,694			126,898,786
	Earnings per common share, basic	$	2.4			$	2.29		$	2.15
	Earnings per common share, diluted	$	2.35			$	2.27		$	2.15
	_______________
	(a)	For the years ended December 31, 2014, 2013 and 2012, we had no antidilutive securities.
Supplemental Cash Flow Information
		Year Ended December 31,
		2014				2013			2012
		(In Thousands)
	CASH PAID FOR (RECEIVED FROM):
	Interest on financing activities, net of amount capitalized	$	160,292			$	148,691		$	143,564
	Interest on financing activities of VIEs	12,183				13,892			16,214
	Income taxes, net of refunds	458				(11		)	(4,378		)
	NON-CASH INVESTING TRANSACTIONS:
	Property, plant and equipment additions	143,192				127,544			89,354
	Property, plant and equipment of VIEs	(7,342		)		(14,282		)	—
	NON-CASH FINANCING TRANSACTIONS:
	Issuance of common stock for reinvested dividends and compensation plans	9,155				9,641			9,089
	Deconsolidation of VIEs	(7,342		)		(14,282		)	—
	Assets acquired through capital leases	8,717				334			10,683

Summary_Of_Significant_Account2

Summary Of Significant Accounting Policies (Tables)	12 Months Ended
	Dec. 31, 2014
Accounting Policies [Abstract]
Fuel Inventory and Supplies	Following are the balances for fuel inventory and supplies stated separately.
		As of December 31,
		2014				2013
		(In Thousands)
	Fuel inventory	$	70,416			$	78,368
	Supplies	176,990				161,143
	Fuel inventory and supplies	$	247,406			$	239,511
Allowance For Funds Used During Construction	We credit other income (for equity funds) and interest expense (for borrowed funds) for the amount of AFUDC capitalized as construction cost on the accompanying consolidated statements of income as follows:
		Year Ended December 31,
		2014				2013			2012
		(Dollars In Thousands)
	Borrowed funds	$	12,044			$	11,706		$	10,399
	Equity funds	17,029				14,143			11,706
	Total	$	29,073			$	25,849		$	22,105
	Average AFUDC Rates	6.7		%		4.8		%	5		%
Depreciable Lives of Property, Plant and Equipment	Depreciable lives of property, plant and equipment are as follows.
			Years
	Fossil fuel generating facilities		6	to	78
	Nuclear fuel generating facility		55	to	71
	Wind generating facilities		19	to	20
	Transmission facilities		15	to	75
	Distribution facilities		22	to	68
	Other		5	to	30
Cash Surrender Value of Life Insurance	We recorded on our consolidated balance sheets in other long-term assets the following amounts related to corporate-owned life insurance (COLI) policies.
		As of December 31,
		2014				2013
		(In Thousands)
	Cash surrender value of policies	$	1,306,777			$	1,289,457
	Borrowings against policies	(1,173,956		)		(1,156,341		)
	Corporate-owned life insurance, net	$	132,821			$	133,116
Reconciliation Of Basic And Diluted Earnings Per Share	The following table reconciles our basic and diluted EPS from net income.
		Year Ended December 31,
		2014				2013			2012
		(Dollars In Thousands, Except Per Share Amounts)
	Net income	$	322,325			$	300,863		$	282,462
	Less: Net income attributable to noncontrolling interests	9,066				8,343			7,316
	Net income attributable to Westar Energy, Inc.	313,259				292,520			275,146
	Less: Preferred dividends	—				—			1,616
	Net income allocated to RSUs	790				810			778
	Net income allocated to common stock	$	312,469			$	291,710		$	272,752
	Weighted average equivalent common shares outstanding – basic	130,014,941				127,462,994			126,711,869
	Effect of dilutive securities:
	RSUs	181,397				17,195			97,757
	Forward sale agreements	2,628,187				818,505			89,160
	Weighted average equivalent common shares outstanding – diluted (a)	132,824,525				128,298,694			126,898,786
	Earnings per common share, basic	$	2.4			$	2.29		$	2.15
	Earnings per common share, diluted	$	2.35			$	2.27		$	2.15
	_______________
	(a)	For the years ended December 31, 2014, 2013 and 2012, we had no antidilutive securities.
Supplemental Cash Flow Information
		Year Ended December 31,
		2014				2013			2012
		(In Thousands)
	CASH PAID FOR (RECEIVED FROM):
	Interest on financing activities, net of amount capitalized	$	160,292			$	148,691		$	143,564
	Interest on financing activities of VIEs	12,183				13,892			16,214
	Income taxes, net of refunds	458				(11		)	(4,378		)
	NON-CASH INVESTING TRANSACTIONS:
	Property, plant and equipment additions	143,192				127,544			89,354
	Property, plant and equipment of VIEs	(7,342		)		(14,282		)	—
	NON-CASH FINANCING TRANSACTIONS:
	Issuance of common stock for reinvested dividends and compensation plans	9,155				9,641			9,089
	Deconsolidation of VIEs	(7,342		)		(14,282		)	—
	Assets acquired through capital leases	8,717				334			10,683

Rate_Matters_And_Regulation_Ta

Rate Matters And Regulation (Tables)	12 Months Ended
	Dec. 31, 2014
Regulated Operations [Abstract]
Schedule Of Regulatory Assets And Liabilities [Table Text Block]	Regulatory assets and liabilities reflected on our consolidated balance sheets are as follows.
		As of December 31,
		2014		2013
		(In Thousands)
	Regulatory Assets:
	Deferred employee benefit costs	$	435,590	$	277,122
	Amounts due from customers for future income taxes, net	153,984		163,742
	Depreciation	68,422		71,047
	Debt reacquisition costs	61,079		63,882
	Ad valorem tax	39,428		34,492
	Treasury yield hedges	26,614		27,594
	Asset retirement obligations	26,106		23,555
	Disallowed plant costs	15,809		15,964
	Wolf Creek outage	11,165		29,026
	Energy efficiency program costs	8,933		14,477
	Retail energy cost adjustment	—		22,138
	Other regulatory assets	12,648		12,375
	Total regulatory assets	$	859,778	$	755,414
	Regulatory Liabilities:
	Removal costs	$	88,242	$	114,148
	Deferred regulatory gain from sale leaseback	81,055		86,551
	Nuclear decommissioning	43,641		43,272
	Retail energy cost adjustment	33,274		15,414
	Jurisdictional allowance for funds used during construction	33,103		7,893
	La Cygne leasehold dismantling costs	22,918		20,505
	Other post-retirement benefits costs	15,473		19,000
	Kansas tax credits	12,725		11,076
	Gain on sale of oil	2,337		4,278
	Fuel supply and electricity contracts	1,738		2,635
	Other regulatory liabilities	8,979		4,784
	Total regulatory liabilities	$	343,485	$	329,556

Financial_Instruments_and_Trad1

Financial Instruments and Trading Securities (Tables)	12 Months Ended
	Dec. 31, 2014
Financial And Derivative Instruments and Trading Securities [Abstract]
Carrying Values And Fair Values Of Financial Instruments	The following table provides the carrying values and measured fair values of our fixed-rate debt.
		As of December 31, 2014					As of December 31, 2013
		Carrying Value			Fair Value		Carrying Value			Fair Value
		(In Thousands)
	Fixed-rate debt	$	3,105,000		$	3,488,410	$	3,102,500		$	3,294,209
	Fixed-rate debt of VIEs	194,204			213,579		221,682			241,241
Fair Value Of Assets And Liabilities	The following table provides the amounts and their corresponding level of hierarchy for our assets that are measured at fair value.
	As of December 31, 2014	Level 1			Level 2		Level 3			Total
		(In Thousands)
	Assets:
	Nuclear Decommissioning Trust:
	Domestic equity funds	$	—		$	54,925	$	6,047		$	60,972
	International equity funds	—			30,791		—			30,791
	Core bond fund	—			19,289		—			19,289
	High-yield bond fund	—			13,198		—			13,198
	Emerging market bond fund	—			10,988		—			10,988
	Other fixed income fund	—			4,779		—			4,779
	Combination debt/equity/other funds	—			18,141		—			18,141
	Alternative investment fund	—			—		16,970			16,970
	Real estate securities fund	—			—		9,548			9,548
	Cash equivalents	340			—		—			340
	Total Nuclear Decommissioning Trust	340			152,111		32,565			185,016
	Trading Securities:
	Domestic equity funds	—			18,698		—			18,698
	International equity fund	—			4,252		—			4,252
	Core bond fund	—			12,379		—			12,379
	Cash equivalents	168			—		—			168
	Total Trading Securities	168			35,329		—			35,497
	Total Assets Measured at Fair Value	$	508		$	187,440	$	32,565		$	220,513
	As of December 31, 2013
	Assets:
	Nuclear Decommissioning Trust:
	Domestic equity funds	$	—		$	49,957	$	5,817		$	55,774
	International equity funds	—			31,816		—			31,816
	Core bond fund	—			18,107		—			18,107
	High-yield bond fund	—			12,902		—			12,902
	Emerging market bond fund	—			11,055		—			11,055
	Other fixed income fund	—			4,690		—			4,690
	Combination debt/equity/other funds	—			17,093		—			17,093
	Alternative investment fund	—			—		15,675			15,675
	Real estate securities fund	—			—		8,511			8,511
	Cash equivalents	2			—		—			2
	Total Nuclear Decommissioning Trust	2			145,620		30,003			175,625
	Trading Securities:
	Domestic equity funds	—			18,075		—			18,075
	International equity fund	—			4,519		—			4,519
	Core bond fund	—			12,166		—			12,166
	Cash equivalents	166			—		—			166
	Total Trading Securities	166			34,760		—			34,926
	Total Assets Measured at Fair Value	$	168		$	180,380	$	30,003		$	210,551
Reconciliations Of Assets And Liabilities At Fair Value	The following table provides reconciliations of assets held in the NDT measured at fair value using significant level 3 inputs for the years ended December 31, 2014 and 2013.
		Domestic			Alternative Investment Fund		Real Estate			Net
		Equity Funds					Securities Fund			Balance
		(In Thousands)
	Balance as of December 31, 2013	$	5,817		$	15,675	$	8,511		$	30,003
	Total realized and unrealized gains included in:
	Regulatory liabilities	391			1,295		1,037			2,723
	Purchases	335			—		351			686
	Sales	(496		)	—		(351		)	(847		)
	Balance as of December 31, 2014	$	6,047		$	16,970	$	9,548		$	32,565
	Balance as of December 31, 2012	$	4,899		$	—	$	7,865		$	12,764
	Total realized and unrealized gains included in:
	Regulatory liabilities	940			675		646			2,261
	Purchases	341			15,000		287			15,628
	Sales	(363		)	—		(287		)	(650		)
	Balance as of December 31, 2013	$	5,817		$	15,675	$	8,511		$	30,003
Unrealized Gains And Losses On Financial Statements	The following table summarizes the unrealized gains and losses we recorded to regulatory liabilities on our consolidated financial statements during the years ended December 31, 2014 and 2013, attributed to level 3 assets and liabilities.
		Domestic			Alternative Investment Fund		Real Estate			Net
		Equity Funds					Securities Fund			Balance
		(In Thousands)
	Year ended December 31, 2014	$	(105	)	$	1,296	$	685		$	1,876
	Year ended December 31, 2013	577			675		359			1,611
Investments In Financial Instruments	The following table provides additional information on these investments.
		As of December 31, 2014					As of December 31, 2013						As of December 31, 2014
		Fair Value			Unfunded		Fair Value			Unfunded			Redemption	Length of
					Commitments					Commitments			Frequency	Settlement
		(In Thousands)
	Nuclear Decommissioning Trust:
	Domestic equity funds	$	6,047		$	2,348	$	5,817		$	2,683		(a)	(a)
	Alternative investment fund	16,970			—		15,675			—			(b)	(b)
	Real estate securities fund	9,548			—		8,511			—			Quarterly	80 days
	Total Nuclear Decommissioning Trust	$	32,565		$	2,348	$	30,003		$	2,683
	Trading Securities:
	Domestic equity funds	$	18,698		$	—	$	18,075		$	—		Upon Notice	1 day
	International equity funds	4,252			—		4,519			—			Upon Notice	1 day
	Core bond fund	12,379			—		12,166			—			Upon Notice	1 day
	Total Trading Securities	35,329			—		34,760			—
	Total	$	67,894		$	2,348	$	64,763		$	2,683
	_______________
	(a)	This investment is in three long-term private equity funds that do not permit early withdrawal. Our investments in these funds cannot be distributed until the underlying investments have been liquidated which may take years from the date of initial liquidation. Two funds have begun to make distributions. Our initial investment in the third fund occurred in the third quarter of 2013. This fund's term will be 15 years, subject to the general partner's right to extend the term for up to three additional one-year periods.
	(b)	This fund has an initial lock-up period of 24 months, which began in April 2013. Redemptions are allowed, on a quarterly basis, after 24 months at the sole discretion of the fund's board of directors. A 65-day notice of redemption is required. There is a holdback on final redemptions.

Financial_Investments_Tables

Financial Investments (Tables)	12 Months Ended
	Dec. 31, 2014
Investments [Abstract]
Cost And Fair Value Of Available-For-Sale Securities	The following table presents the cost, gross unrealized gains and losses, fair value and allocation of investments in the NDT fund as of December 31, 2014 and 2013.
						Gross Unrealized
	Security Type		Cost			Gain			Loss				Fair Value			Allocation
			(Dollars In Thousands)
	As of December 31, 2014
	Domestic equity funds		$	46,126		$	14,853		$	(7	)		$	60,972		33	%
	International equity funds		27,521			3,683			(413		)		30,791			17	%
	Core bond fund		18,811			478			—				19,289			10	%
	High-yield bond fund		13,342			—			(144		)		13,198			7	%
	Emerging market bond fund		12,556			—			(1,568		)		10,988			6	%
	Other fixed income fund		4,798			—			(19		)		4,779			3	%
	Combination debt/equity/other funds		14,975			3,786			(620		)		18,141			10	%
	Alternative investment fund		15,000			1,970			—				16,970			9	%
	Real estate securities fund		10,619			—			(1,071		)		9,548			5	%
	Cash equivalents		340			—			—				340			<1%
	Total		$	164,088		$	24,770		$	(3,842	)		$	185,016		100	%
	As of December 31, 2013
	Domestic equity funds		$	40,976		$	14,799		$	(1	)		$	55,774		32	%
	International equity funds		26,581			5,266			(31		)		31,816			18	%
	Core bond fund		18,287			—			(180		)		18,107			10	%
	High-yield bond fund		12,275			627			—				12,902			7	%
	Emerging market bond fund		12,207			—			(1,152		)		11,055			6	%
	Other fixed income fund		4,684			6			—				4,690			3	%
	Combination debt/equity/other funds		14,964			2,380			(251		)		17,093			10	%
	Alternative investment fund		15,000			675			—				15,675			9	%
	Real estate securities fund		10,268			—			(1,757		)		8,511			5	%
	Cash equivalents		2			—			—				2			<1%
	Total		$	155,244		$	23,753		$	(3,372	)		$	175,625		100	%
Fair Value And Gross Unrealized Losses Of Available-For-Sale Securities	The following table presents the fair value and the gross unrealized losses of the available-for-sale securities held in the NDT fund aggregated by investment category and the length of time that individual securities have been in a continuous unrealized loss position as of December 31, 2014 and 2013.
		Less than 12 Months						12 Months or Greater							Total
		Fair Value			Gross			Fair Value				Gross			Fair Value			Gross
					Unrealized							Unrealized						Unrealized
					Losses							Losses						Losses
		(In Thousands)
	As of December 31, 2014
	Domestic equity funds	$	—		$	—		$	263			$	(7	)	$	263		$	(7	)
	International equity funds	5,905			(413		)	—				—			5,905			(413		)
	High-yield bond fund	13,198			(144		)	—				—			13,198			(144		)
	Emerging market bond fund	—			—			10,988				(1,568		)	10,988			(1,568		)
	Other fixed income fund	4,779			(19		)	—				—			4,779			(19		)
	Combination debt/equity/other funds	—			—			5,892				(620		)	5,892			(620		)
	Real estate securities fund	—			—			9,548				(1,071		)	9,548			(1,071		)
	Total	$	23,882		$	(576	)	$	26,691			$	(3,266	)	$	50,573		$	(3,842	)
	As of December 31, 2013
	Domestic equity funds	$	59		$	(1	)	$	—			$	—		$	59		$	(1	)
	International equity funds	6,244			(31		)	—				—			6,244			(31		)
	Core bond fund	18,107			(180		)	—				—			18,107			(180		)
	Emerging market bond fund	11,055			(1,152		)	—				—			11,055			(1,152		)
	Combination debt/equity/other funds	6,283			(251		)	—				—			6,283			(251		)
	Real estate securities fund	—			—			8,511				(1,757		)	8,511			(1,757		)
	Total	$	41,748		$	(1,615	)	$	8,511			$	(1,757	)	$	50,259		$	(3,372	)

Property_Plant_And_Equipment_T

Property, Plant And Equipment (Tables)	12 Months Ended
	Dec. 31, 2014
Public Utility, Property, Plant and Equipment [Line Items]
Schedule of Public Utility Property, Plant, and Equipment	The following is a summary of our property, plant and equipment balance.
		As of December 31,
		2014			2013
		(In Thousands)
	Electric plant in service	$	10,620,292		$	9,753,787
	Electric plant acquisition adjustment	802,318			802,318
	Accumulated depreciation	(4,112,483		)	(3,971,735		)
		7,310,127			6,584,370
	Construction work in progress	773,144			904,586
	Nuclear fuel, net	79,637			62,960
	Net property, plant and equipment	$	8,162,908		$	7,551,916
Variable Interest Entity [Member]
Public Utility, Property, Plant and Equipment [Line Items]
Schedule of Public Utility Property, Plant, and Equipment	The following is a summary of property, plant and equipment of VIEs.
		As of December 31,
		2014			2013
		(In Thousands)
	Electric plant of VIEs	$	497,999		$	513,793
	Accumulated depreciation of VIEs	(219,426		)	(217,167		)
	Net property, plant and equipment of VIEs	$	278,573		$	296,626

Joint_Ownership_of_Utility_Pla1

Joint Ownership of Utility Plants Joint Ownership of Utility Plants (Tables)	12 Months Ended
	Dec. 31, 2014
Jointly Owned Utility Plant, Net Ownership Amount [Abstract]
Schedule of Jointly Owned Utility Plants	Information relative to our ownership interests in these facilities as of December 31, 2014, is shown in the table below.
	Plant		In-Service	Investment		Accumulated		Construction		Net	Ownership
			Dates			Depreciation		Work in Progress		MW	Percentage
				(Dollars in Thousands)
	La Cygne unit 1 (a)		Jun-73	$	345,866	$	157,550	$	368,445	367	50
	JEC unit 1 (a)		Jul-78	789,142		189,973		11,150		661	92
	JEC unit 2 (a)		May-80	540,871		190,769		3,189		658	92
	JEC unit 3 (a)		May-83	709,497		309,540		3,246		664	92
	Wolf Creek (b)		Sept. 1985	1,818,005		788,602		73,333		549	47
	State Line (c)		Jun-01	100,671		53,347		22		193	40
	Total			$	4,304,052	$	1,689,781	$	459,385	3,092
	_______________
	(a)	Jointly owned with KCPL. Our 8% leasehold interest in Jeffrey Energy Center (JEC) that is consolidated as a VIE is reflected in the net megawatts (MW) and ownership percentage provided above, but not in the other amounts in the table.
	(b)	Jointly owned with KCPL and Kansas Electric Power Cooperative, Inc.
	(c)    Jointly owned with Empire District Electric Company.

ShortTerm_Debt_Tables

Short-Term Debt (Tables)	12 Months Ended
	Dec. 31, 2014
Debt Disclosure [Abstract]
Short-term Debt Additional Information	Additional information regarding our short-term debt is as follows.
		As of December 31,
		2014			2013
		(Dollars in Thousands)
	Weighted average short-term debt outstanding during the year	$	232,336		$	228,352
	Weighted daily average interest rates during the year, excluding fees	0.3		%	0.39		%

LongTerm_Debt_Tables

Long-Term Debt (Tables)	12 Months Ended
	Dec. 31, 2014
Long-term Debt, Unclassified [Abstract]
Long-term Debt Outstanding	The following table summarizes our long-term debt outstanding.
		As of December 31,
		2014			2013
		(In Thousands)
	Westar Energy
	First mortgage bond series:
	6.00% due 2014	$	—		$	250,000
	5.15% due 2017	125,000			125,000
	8.625% due 2018	300,000			300,000
	5.10% due 2020	250,000			250,000
	5.95% due 2035	125,000			125,000
	5.875% due 2036	150,000			150,000
	4.125% due 2042	550,000			550,000
	4.10% due 2043	430,000			250,000
	4.625% due 2043	250,000			250,000
		2,180,000			2,250,000
	Pollution control bond series:
	Variable due 2032, 0.06% as of December 31, 2014; 0.12% as of December 31, 2013	45,000			45,000
	Variable due 2032, 0.08% as of December 31, 2014; 0.12% as of December 31, 2013	30,500			30,500
		75,500			75,500
	KGE
	First mortgage bond series:
	6.70% due 2019	300,000			300,000
	6.15% due 2023	50,000			50,000
	6.53% due 2037	175,000			175,000
	6.64% due 2038	100,000			100,000
	4.30% due 2044	250,000			—
		875,000			625,000
	Pollution control bond series:
	Variable due 2027, 0.08% as of December 31, 2014; 0.10% as of December 31, 2013	21,940			21,940
	5.30% due 2031	—			108,600
	5.30% due 2031	—			18,900
	4.85% due 2031	50,000			50,000
	5.00% due 2031	—			50,000
	Variable due 2032, 0.08% as of December 31, 2014; 0.10% as of December 31, 2013	14,500			14,500
	Variable due 2032, 0.08% as of December 31, 2014; 0.10% as of December 31, 2013	10,000			10,000
		96,440			273,940
	Total long-term debt	3,226,940			3,224,440
	Unamortized debt discount (a)	(11,401		)	(5,482		)
	Long-term debt due within one year	—			(250,000		)
	Long-term debt, net	$	3,215,539		$	2,968,958
	Variable Interest Entities
	6.99% due 2014 (b)	—			316
	5.92% due 2019 (b)	8,413			13,243
	5.647% due 2021 (b)	185,791			208,123
	Total long-term debt of variable interest entities	194,204			221,682
	Unamortized debt premium (a)	294			599
	Long-term debt of variable interest entities due within one year	(27,933		)	(27,479		)
	Long-term debt of variable interest entities, net	$	166,565		$	194,802
	_______________
	(a) We amortize debt discounts and premiums to interest expense over the term of the respective issues.
	(b) Portions of our payments related to this debt reduce the principal balances each year until maturity.
Schedule of Maturities of Long-term Debt	The principal amounts of our long-term debt maturities as of December 31, 2014, are as follows.
	Year		Long-term debt			Long-term
						debt of  VIEs
			(In Thousands)
	2015		$	—		$	27,933
	2016		—			28,309
	2017		125,000			26,842
	2018		300,000			28,538
	2019		300,000			31,485
	Thereafter		2,501,940			51,097
	Total maturities		$	3,226,940		$	194,204

Taxes_Tables

Taxes (Tables)	12 Months Ended
	Dec. 31, 2014
Income Tax Disclosure [Abstract]
Income Tax Expense Components	Income tax expense is comprised of the following components.
		Year Ended December 31,
		2014				2013				2012
		(In Thousands)
	Income Tax Expense (Benefit):
	Current income taxes:
	Federal	$	416			$	135			$	(691	)
	State	(597		)		279				579
	Deferred income taxes:
	Federal	124,923				102,030				102,960
	State	29,657				24,443				26,300
	Investment tax credit amortization	(3,129		)		(3,166		)		(3,012		)
	Income tax expense	$	151,270			$	123,721			$	126,136
Deferred Tax Assets and Liabilities	Deferred tax assets and liabilities are reflected on our consolidated balance sheets as follows.
		As of December 31,
		2014				2013
		(In Thousands)
	Current deferred tax assets	$	29,636			$	37,954
	Non-current deferred tax liabilities	1,475,487				1,363,148
	Net deferred tax liabilities	$	1,445,851			$	1,325,194
	The tax effect of the temporary differences and carryforwards that comprise our deferred tax assets and deferred tax liabilities are summarized in the following table.
		As of December 31,
		2014				2013
		(In Thousands)
	Deferred tax assets:
	Tax credit carryforward (a)	$	257,827			$	212,635
	Net operating loss carryforward (b)	179,285				108,885
	Deferred employee benefit costs	158,102				85,720
	Deferred state income taxes	66,557				57,243
	Deferred regulatory gain on sale-leaseback	35,706				38,124
	Deferred compensation	29,315				30,022
	Alternative minimum tax carryforward (c)	24,114				35,666
	Accrued liabilities	23,048				17,396
	Disallowed costs	10,829				11,453
	LaCygne dismantling cost	9,064				8,110
	Capital loss carryforward (d)	1,981				3,447
	Other	27,689				20,058
	Total gross deferred tax assets	823,517				628,759
	Less: Valuation allowance (e)	1,981				3,504
	Deferred tax assets	$	821,536			$	625,255
	Deferred tax liabilities:
	Accelerated depreciation	$	1,664,367			$	1,390,669
	Acquisition premium	163,894				171,907
	Deferred employee benefit costs	158,102				85,720
	Amounts due from customers for future income taxes, net	153,984				163,742
	Deferred state income taxes	59,170				51,504
	Debt reacquisition costs	20,102				19,985
	Storm costs	15,713				21,165
	Pension expense tracker	14,187				21,230
	Other	17,868				24,527
	Total deferred tax liabilities	$	2,267,387			$	1,950,449
	Net deferred tax liabilities	$	1,445,851			$	1,325,194
	_______________
	(a)	Based on filed tax returns and amounts expected to be reported in current year tax returns (December 31, 2014), we had available federal general business tax credits of $73.5 million and state investment tax credits of $184.3 million. The federal general business tax credits were primarily generated from production tax credits. These tax credits expire beginning in 2020 and ending in 2034. The state investment tax credits expire beginning in 2017 and ending in 2030.
	(b)	As of December 31, 2014, we had a federal net operating loss carryforward of $452.8 million, which is available to offset federal taxable income. The net operating losses will expire beginning in 2031 and ending in 2034.
	(c)	As of December 31, 2014, we had available an alternative minimum tax credit carryforward of $24.1 million, which has an unlimited carryforward period.
	(d)	As of December 31, 2014, we had an unused capital loss carryforward of $5.0 million that is available to offset future capital gains. The capital losses will expire in 2016.
	(e)	As we do not expect to realize any significant capital gains in the future, we have established a valuation allowance of $2.0 million. The total valuation allowance related to the deferred tax assets was $2.0 million as of December 31, 2014, and $3.5 million as of December 31, 2013.
Effective Income Tax Rate Reconciliation	The difference between the effective income tax rates and the federal statutory income tax rates are as follows.
		Year Ended December 31,
		2014			2013			2012
	Statutory federal income tax rate	35	%		35	%		35	%
	Effect of:
	State income taxes	4			3.8			4.3
	Corporate-owned life insurance policies	(4.0	)		(5.4	)		(4.9	)
	Production tax credits	(2.1	)		(2.3	)		(2.4	)
	Flow through depreciation for plant-related differences	2			2.2			1.4
	AFUDC equity	(1.3	)		(1.2	)		(1.0	)
	Amortization of federal investment tax credits	(0.7	)		(0.7	)		(0.7	)
	Capital loss utilization carryforward	(0.3	)		(1.1	)		(0.3	)
	Liability for unrecognized income tax benefits	(0.2	)		0.1			0.2
	Other	(0.5	)		(1.3	)		(0.7	)
	Effective income tax rate	31.9	%		29.1	%		30.9	%
Unrecognized Income Tax Benefits Reconciliation	A reconciliation of the beginning and ending amounts of unrecognized income tax benefits is as follows:
		2014				2013				2012
		(In Thousands)
	Unrecognized income tax benefits as of January 1	$	1,703			$	1,219			$	2,483
	Additions based on tax positions related to the current year	872				224				373
	Additions for tax positions of prior years	813				325				—
	Reductions for tax positions of prior years	(200		)		(65		)		(1,637		)
	Settlements	—				—				—
	Unrecognized income tax benefits as of December 31	$	3,188			$	1,703			$	1,219

Employee_Benefit_Plans_Tables

Employee Benefit Plans (Tables)	12 Months Ended
	Dec. 31, 2014
Defined Benefit Plan Disclosure [Line Items]
Schedule Of Benefit Obligation Fair Value Of Plan Assets And Amounts Recognized In Balance Sheet	The following tables summarize the status of our pension and post-retirement benefit plans.
		Pension Benefits								Post-retirement Benefits
	As of December 31,	2014				2013				2014				2013
		(In Thousands)
	Change in Benefit Obligation:
	Benefit obligation, beginning of year	$	823,780			$	928,708			$	133,061			$	152,564
	Service cost	16,218				21,420				1,381				2,028
	Interest cost	41,600				38,520				6,351				6,007
	Plan participants’ contributions	—				—				4,232				2,961
	Benefits paid	(39,225		)		(36,529		)		(12,184		)		(10,968		)
	Actuarial (gains) losses	188,272				(128,339		)		16,509				(19,531		)
	Amendments	—				—				(7,834		)		—
	Benefit obligation, end of year (a)	$	1,030,645			$	823,780			$	141,516			$	133,061
	Change in Plan Assets:
	Fair value of plan assets, beginning of year	$	609,817			$	547,931			$	121,766			$	106,793
	Actual return on plan assets	61,291				68,151				7,189				17,361
	Employer contributions	26,400				27,500				—				5,318
	Plan participants’ contributions	—				—				4,074				2,830
	Benefits paid	(36,367		)		(33,765		)		(11,680		)		(10,536		)
	Fair value of plan assets, end of year	$	661,141			$	609,817			$	121,349			$	121,766
	Funded status, end of year	$	(369,504	)		$	(213,963	)		$	(20,167	)		$	(11,295	)
	Amounts Recognized in the Balance Sheets Consist of:
	Current liability	$	(2,716	)		$	(2,740	)		$	(246	)		$	(242	)
	Noncurrent liability	(366,788		)		(211,223		)		(19,921		)		(11,053		)
	Net amount recognized	$	(369,504	)		$	(213,963	)		$	(20,167	)		$	(11,295	)
	Amounts Recognized in Regulatory Assets Consist of:
	Net actuarial loss (gain)	$	329,572			$	186,365			$	(2,253	)		$	(18,890	)
	Prior service cost	2,867				3,393				3,585				13,942
	Transition obligation	—				—				—				—
	Net amount recognized	$	332,439			$	189,758			$	1,332			$	(4,948	)
	_______________
	(a)	As of December 31, 2014 and 2013, pension benefits include non-qualified benefit obligations of $29.8 million and $27.0 million, respectively, which are funded by a trust containing assets of $35.5 million and $34.9 million, respectively, classified as trading securities. The assets in the aforementioned trust are not included in the table above. See Notes 4 and 5, "Financial Instruments and Trading Securities" and "Financial Investments," respectively, for additional information regarding these amounts.
Schedule Of Benefit Obligations In Excess Of Fair Value Of Plan Assets And Assumptions Used For Benefit Obligation
		Pension Benefits								Post-retirement Benefits
	As of December 31,	2014				2013				2014				2013
		(Dollars in Thousands)
	Pension Plans With a Projected Benefit Obligation In Excess of Plan Assets:
	Projected benefit obligation	$	1,030,645			$	823,780			$	—			$	—
	Fair value of plan assets	661,141				609,817				—				—
	Pension Plans With an Accumulated Benefit Obligation In Excess of Plan Assets:
	Accumulated benefit obligation	$	914,800			$	732,150			—				—
	Fair value of plan assets	661,141				609,817				—				—
	Post-retirement Plans With an Accumulated Post-retirement Benefit Obligation In Excess of Plan Assets:
	Accumulated post-retirement benefit obligation	—				—				$	141,516			$	133,061
	Fair value of plan assets	—				—				121,349				121,766
	Weighted-Average Actuarial Assumptions used to Determine Net Periodic Benefit Obligation:
	Discount rate	4.17		%		5.07		%		4.1		%		4.88		%
	Compensation rate increase	4		%		4		%		—				—
Schedule Of Net Benefit Costs And Assumptions Used For Net Periodic Cost	Following is additional information regarding our pension and post-retirement benefit plans.
			Pension Benefits												Post-retirement Benefits
	Year Ended December 31,		2014				2013				2012				2014			2013			2012
			(Dollars in Thousands)
	Components of Net Periodic Cost (Benefit):
	Service cost		$	16,218			$	21,420			$	19,556			$	1,381		$	2,028		$	2,057
	Interest cost		41,600				38,520				39,576				6,351			6,007			6,298
	Expected return on plan assets		(36,438		)		(33,405		)		(32,283		)		(6,576		)	(6,691		)	(5,491		)
	Amortization of unrecognized:
	Transition obligation, net		—				—				—				—			325			3,912
	Prior service costs		526				601				612				2,524			2,524			2,524
	Actuarial loss, net		19,362				33,914				32,778				(742		)	1,125			1,503
	Net periodic cost before regulatory adjustment		41,268				61,050				60,239				2,938			5,318			10,803
	Regulatory adjustment (a)		15,479				3,693				(6,523		)		4,499			2,922			23
	Net periodic cost		$	56,747			$	64,743			$	53,716			$	7,437		$	8,240		$	10,826
	Other Changes in Plan Assets and Benefit Obligations Recognized in Regulatory Assets:
	Current year actuarial (gain)/loss		$	162,569			$	(163,086	)		$	18,451			$	15,896		$	(30,201	)	$	(4,239	)
	Amortization of actuarial (loss)		(19,362		)		(33,914		)		(32,778		)		742			(1,125		)	(1,503		)
	Current year prior service cost		—				—				—				(7,834		)	—			—
	Amortization of prior service costs		(526		)		(601		)		(612		)		(2,524		)	(2,525		)	(2,524		)
	Amortization of transition obligation		—				—				—				—			(325		)	(3,912		)
	Total recognized in regulatory assets		$	142,681			$	(197,601	)		$	(14,939	)		$	6,280		$	(34,176	)	$	(12,178	)
	Total recognized in net periodic cost and regulatory assets		$	199,428			$	(132,858	)		$	38,777			$	13,717		$	(25,936	)	$	(1,352	)
	Weighted-Average Actuarial Assumptions used to Determine Net Periodic Cost (Benefit):
	Discount rate		5.07		%		4.13		%		4.5		%		4.88		%	3.99		%	4.25		%
	Expected long-term return on plan assets		6.5		%		6.5		%		6.5		%		6		%	6		%	6		%
	Compensation rate increase		4		%		4		%		4		%		4		%	4		%	—		%
	_______________
	(a)	The regulatory adjustment represents the difference between current period pension or post-retirement benefit expense and the amount of such expense recognized in setting our prices.
Schedule Of Amounts To Be Amortized From Regulatory Assets To Net Periodic Cost	We estimate that we will amortize the following amounts from regulatory assets into net periodic cost in 2015.
		Pension				Post-retirement
		Benefits				Benefits
		(In Thousands)
	Actuarial loss	$	32,131			$	379
	Prior service cost	520				455
	Total	$	32,651			$	834
Schedule of Health Care Cost Trend Rates	For measurement purposes, the assumed annual health care cost growth rates were as follows.
		As of December 31,
		2014 (a)		2013
	Health care cost trend rate assumed for next year	—		7.50%
	Rate to which the cost trend rate is assumed to decline (the ultimate trend rate)	—		5.00%
	Year that the rate reaches the ultimate trend rate	—		2019
Schedule of Effect of One-Percentage-Point Change in Assumed Health Care Cost Trend Rates	The health care cost trend rate affects the projected benefit obligation. A 1% change in assumed health care cost growth rates would have effects shown in the following table.
		One-Percentage-				One-Percentage-
		Point Increase				Point Decrease
		(In Thousands)
	Effect on total of service and interest cost	$	134			$	(120	)
	Effect on post-retirement benefit obligation (a)	—				—
Schedule of Effect of Significant Unobservable Inputs, Changes in Plan Assets	The following table provides a reconciliation of pension plan assets measured at fair value using significant level 3 inputs for the years ended December 31, 2014 and 2013.
		Domestic				Alternative Investment				Real Estate				Total
		Equity Funds				Funds				Securities Fund
		(In Thousands)
	Balance as of December 31, 2013	$	22,488			$	39,171			$	24,022			$	85,681
	Actual gain (loss) on plan assets:
	Relating to assets still held at the reporting date	(154		)		1,970				2,630				4,446
	Relating to assets sold during the period	1,365				—				29				1,394
	Purchases, issuances and settlements, net	297				—				(242		)		55
	Balance as of December 31, 2014	$	23,996			$	41,141			$	26,439			$	91,576
	Balance as of December 31, 2012	$	18,493			$	45,535			$	20,927			$	84,955
	Actual gain (loss) on plan assets:
	Relating to assets still held at the reporting date	3,845				1,936				3,307				9,088
	Relating to assets sold during the period	—				826				—				826
	Purchases, issuances and settlements, net	150				(9,126		)		(212		)		(9,188		)
	Balance as of December 31, 2013	$	22,488			$	39,171			$	24,022			$	85,681
Schedule of Expected Benefit Payments	Cash Flows
	The following table shows the expected cash flows for our pension and post-retirement benefit plans for future years.
	Expected Cash Flows		Pension Benefits								Post-retirement Benefits
			To/(From) Trust				(From)				To/(From) Trust				(From)
							Company Assets								Company Assets
			(In Millions)
	Expected contributions:
	2015		$	42							$	—
	Expected benefit payments:
	2015		$	(35.1	)		$	(2.8	)		$	(8.2	)		$	(0.2	)
	2016		(37.3		)		(2.8		)		(8.3		)		(0.2		)
	2017		(39.5		)		(2.8		)		(8.4		)		(0.2		)
	2018		(41.9		)		(2.7		)		(8.6		)		(0.2		)
	2019		(44.2		)		(2.7		)		(8.7		)		(0.2		)
	2020-2024		(257.8		)		(13.0		)		(43.5		)		(1.0		)
Schedule of Compensation Expense and Income Tax Benefits Related to Stock Compensation Arrangements	The table below shows compensation expense and income tax benefits related to stock-based compensation arrangements that are included in our net income.
		Year Ended December 31,
		2014				2013				2012
		(In Thousands)
	Compensation expense	$	7,193			$	8,121			$	7,203
	Income tax benefits related to stock-based compensation arrangements	2,845				3,212				2,849
Other Postretirement Benefit Plans, Defined Benefit [Member]
Defined Benefit Plan Disclosure [Line Items]
Schedule of Allocation of Plan Assets	The following table provides the fair value of our post-retirement benefit plan assets and the corresponding level of hierarchy as of December 31, 2014 and 2013.
	As of December 31, 2014		Level 1				Level 2				Level 3				Total
			(In Thousands)
	Assets:
	Domestic equity funds		$	—			$	63,600			$	—			$	63,600
	International equity fund		—				14,783				—				14,783
	Core bond funds		—				42,390				—				42,390
	Cash equivalents		—				576				—				576
	Total Assets Measured at Fair Value		$	—			$	121,349			$	—			$	121,349
	As of December 31, 2013
	Assets:
	Domestic equity funds		$	—			$	64,080			$	—			$	64,080
	International equity fund		—				16,018				—				16,018
	Core bond funds		—				41,092				—				41,092
	Cash equivalents		—				576				—				576
	Total Assets Measured at Fair Value		$	—			$	121,766			$	—			$	121,766
Pension Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Schedule of Allocation of Plan Assets	The following table provides the fair value of our pension plan assets and the corresponding level of hierarchy as of December 31, 2014 and 2013.
	As of December 31, 2014		Level 1				Level 2				Level 3				Total
			(In Thousands)
	Assets:
	Domestic equity funds		$	—			$	160,574			$	23,996			$	184,570
	International equity fund		—				82,604				—				82,604
	Core bond funds		—				224,740				—				224,740
	High-yield bond fund		—				20,412				—				20,412
	Emerging market bond fund		—				14,685				—				14,685
	Combination debt/equity/other fund		—				61,632				—				61,632
	Alternative investment funds		—				—				41,141				41,141
	Real estate securities fund		—				—				26,439				26,439
	Cash equivalents		—				4,918				—				4,918
	Total Assets Measured at Fair Value		$	—			$	569,565			$	91,576			$	661,141
	As of December 31, 2013
	Assets:
	Domestic equity funds		$	—			$	161,272			$	22,488			$	183,760
	International equity fund		—				75,872				—				75,872
	Core bond funds		—				191,506				—				191,506
	High-yield bond fund		—				20,796				—				20,796
	Emerging market bond fund		—				13,113				—				13,113
	Combination debt/equity/other fund		—				58,336				—				58,336
	Alternative investment funds		—				—				39,171				39,171
	Real estate securities fund		—				—				24,022				24,022
	Cash equivalents		—				3,241				—				3,241
	Total Assets Measured at Fair Value		$	—			$	524,136			$	85,681			$	609,817
RSU Awards With Performance Measures [Member]
Defined Benefit Plan Disclosure [Line Items]
Schedule of Share-based Compensation, Restricted Stock Units Award Activity	During the years ended December 31, 2014, 2013 and 2012, our RSU activity for awards with performance measures was as follows.
		As of December 31,
		2014							2013							2012
		Shares			Weighted-				Shares			Weighted-				Shares		Weighted-
					Average							Average						Average
					Grant Date							Grant Date						Grant Date
					Fair Value							Fair Value						Fair Value
		(Shares In Thousands)
	Nonvested balance, beginning of year	350.1			$	30.35			340.1			$	29.2			324.2		$	28.31
	Granted	126.1			35.97				134.4			31.54				122.3		28.84
	Vested	(108.2	)		30.56				(112.5	)		28.29				(88.2	)	25.46
	Forfeited	(22.9	)		30.7				(11.9	)		30.45				(18.2	)	29
	Nonvested balance, end of year	345.1			32.31				350.1			30.35				340.1		29.2
RSU Awards With Only Service Requirements [Member]
Defined Benefit Plan Disclosure [Line Items]
Schedule of Share-based Compensation, Restricted Stock Units Award Activity	During the years ended December 31, 2014, 2013 and 2012, our RSU activity for awards with only service requirements was as follows.
		As of December 31,
		2014							2013							2012
		Shares			Weighted-				Shares			Weighted-				Shares		Weighted-
					Average							Average						Average
					Grant Date							Grant Date						Grant Date
					Fair Value							Fair Value						Fair Value
		(Shares In Thousands)
	Nonvested balance, beginning of year	352.5			$	28.38			351.1			$	25.47			368.5		$	23.83
	Granted	131.5			34.53				139.6			31.06				131		27.82
	Vested	(118.2	)		26.19				(125.5	)		23.22				(127.8	)	23.34
	Forfeited	(23.6	)		30				(12.7	)		28.35				(20.6	)	24.4
	Nonvested balance, end of year	342.2			31.38				352.5			28.38				351.1		25.47

Wolf_Creek_Employee_Benefit_Pl1

Wolf Creek Employee Benefit Plans (Tables)	12 Months Ended
	Dec. 31, 2014
Wolf Creek Interim Pension And Post-Retirement Benefit Disclosure [Line Items]
Schedule Of Benefit Obligation Fair Value Of Plan Assets And Amounts Recognized In Balance Sheet	The following tables summarize the status of our pension and post-retirement benefit plans.
		Pension Benefits								Post-retirement Benefits
	As of December 31,	2014				2013				2014				2013
		(In Thousands)
	Change in Benefit Obligation:
	Benefit obligation, beginning of year	$	823,780			$	928,708			$	133,061			$	152,564
	Service cost	16,218				21,420				1,381				2,028
	Interest cost	41,600				38,520				6,351				6,007
	Plan participants’ contributions	—				—				4,232				2,961
	Benefits paid	(39,225		)		(36,529		)		(12,184		)		(10,968		)
	Actuarial (gains) losses	188,272				(128,339		)		16,509				(19,531		)
	Amendments	—				—				(7,834		)		—
	Benefit obligation, end of year (a)	$	1,030,645			$	823,780			$	141,516			$	133,061
	Change in Plan Assets:
	Fair value of plan assets, beginning of year	$	609,817			$	547,931			$	121,766			$	106,793
	Actual return on plan assets	61,291				68,151				7,189				17,361
	Employer contributions	26,400				27,500				—				5,318
	Plan participants’ contributions	—				—				4,074				2,830
	Benefits paid	(36,367		)		(33,765		)		(11,680		)		(10,536		)
	Fair value of plan assets, end of year	$	661,141			$	609,817			$	121,349			$	121,766
	Funded status, end of year	$	(369,504	)		$	(213,963	)		$	(20,167	)		$	(11,295	)
	Amounts Recognized in the Balance Sheets Consist of:
	Current liability	$	(2,716	)		$	(2,740	)		$	(246	)		$	(242	)
	Noncurrent liability	(366,788		)		(211,223		)		(19,921		)		(11,053		)
	Net amount recognized	$	(369,504	)		$	(213,963	)		$	(20,167	)		$	(11,295	)
	Amounts Recognized in Regulatory Assets Consist of:
	Net actuarial loss (gain)	$	329,572			$	186,365			$	(2,253	)		$	(18,890	)
	Prior service cost	2,867				3,393				3,585				13,942
	Transition obligation	—				—				—				—
	Net amount recognized	$	332,439			$	189,758			$	1,332			$	(4,948	)
	_______________
	(a)	As of December 31, 2014 and 2013, pension benefits include non-qualified benefit obligations of $29.8 million and $27.0 million, respectively, which are funded by a trust containing assets of $35.5 million and $34.9 million, respectively, classified as trading securities. The assets in the aforementioned trust are not included in the table above. See Notes 4 and 5, "Financial Instruments and Trading Securities" and "Financial Investments," respectively, for additional information regarding these amounts.
Schedule Of Benefit Obligations In Excess Of Fair Value Of Plan Assets And Assumptions Used For Benefit Obligation
		Pension Benefits								Post-retirement Benefits
	As of December 31,	2014				2013				2014				2013
		(Dollars in Thousands)
	Pension Plans With a Projected Benefit Obligation In Excess of Plan Assets:
	Projected benefit obligation	$	1,030,645			$	823,780			$	—			$	—
	Fair value of plan assets	661,141				609,817				—				—
	Pension Plans With an Accumulated Benefit Obligation In Excess of Plan Assets:
	Accumulated benefit obligation	$	914,800			$	732,150			—				—
	Fair value of plan assets	661,141				609,817				—				—
	Post-retirement Plans With an Accumulated Post-retirement Benefit Obligation In Excess of Plan Assets:
	Accumulated post-retirement benefit obligation	—				—				$	141,516			$	133,061
	Fair value of plan assets	—				—				121,349				121,766
	Weighted-Average Actuarial Assumptions used to Determine Net Periodic Benefit Obligation:
	Discount rate	4.17		%		5.07		%		4.1		%		4.88		%
	Compensation rate increase	4		%		4		%		—				—
Schedule Of Net Benefit Costs And Assumptions Used For Net Periodic Cost	Following is additional information regarding our pension and post-retirement benefit plans.
			Pension Benefits												Post-retirement Benefits
	Year Ended December 31,		2014				2013				2012				2014				2013				2012
			(Dollars in Thousands)
	Components of Net Periodic Cost (Benefit):
	Service cost		$	16,218			$	21,420			$	19,556			$	1,381			$	2,028			$	2,057
	Interest cost		41,600				38,520				39,576				6,351				6,007				6,298
	Expected return on plan assets		(36,438		)		(33,405		)		(32,283		)		(6,576		)		(6,691		)		(5,491		)
	Amortization of unrecognized:
	Transition obligation, net		—				—				—				—				325				3,912
	Prior service costs		526				601				612				2,524				2,524				2,524
	Actuarial loss, net		19,362				33,914				32,778				(742		)		1,125				1,503
	Net periodic cost before regulatory adjustment		41,268				61,050				60,239				2,938				5,318				10,803
	Regulatory adjustment (a)		15,479				3,693				(6,523		)		4,499				2,922				23
	Net periodic cost		$	56,747			$	64,743			$	53,716			$	7,437			$	8,240			$	10,826
	Other Changes in Plan Assets and Benefit Obligations Recognized in Regulatory Assets:
	Current year actuarial (gain)/loss		$	162,569			$	(163,086	)		$	18,451			$	15,896			$	(30,201	)		$	(4,239	)
	Amortization of actuarial (loss)		(19,362		)		(33,914		)		(32,778		)		742				(1,125		)		(1,503		)
	Current year prior service cost		—				—				—				(7,834		)		—				—
	Amortization of prior service costs		(526		)		(601		)		(612		)		(2,524		)		(2,525		)		(2,524		)
	Amortization of transition obligation		—				—				—				—				(325		)		(3,912		)
	Total recognized in regulatory assets		$	142,681			$	(197,601	)		$	(14,939	)		$	6,280			$	(34,176	)		$	(12,178	)
	Total recognized in net periodic cost and regulatory assets		$	199,428			$	(132,858	)		$	38,777			$	13,717			$	(25,936	)		$	(1,352	)
	Weighted-Average Actuarial Assumptions used to Determine Net Periodic Cost (Benefit):
	Discount rate		5.07		%		4.13		%		4.5		%		4.88		%		3.99		%		4.25		%
	Expected long-term return on plan assets		6.5		%		6.5		%		6.5		%		6		%		6		%		6		%
	Compensation rate increase		4		%		4		%		4		%		4		%		4		%		—		%
	_______________
	(a)	The regulatory adjustment represents the difference between current period pension or post-retirement benefit expense and the amount of such expense recognized in setting our prices.
Schedule Of Amounts To Be Amortized From Regulatory Assets To Net Periodic Cost	We estimate that we will amortize the following amounts from regulatory assets into net periodic cost in 2015.
		Pension				Post-retirement
		Benefits				Benefits
		(In Thousands)
	Actuarial loss	$	32,131			$	379
	Prior service cost	520				455
	Total	$	32,651			$	834
Schedule of Health Care Cost Trend Rates	For measurement purposes, the assumed annual health care cost growth rates were as follows.
		As of December 31,
		2014 (a)		2013
	Health care cost trend rate assumed for next year	—		7.50%
	Rate to which the cost trend rate is assumed to decline (the ultimate trend rate)	—		5.00%
	Year that the rate reaches the ultimate trend rate	—		2019
Schedule of Effect of One-Percentage-Point Change in Assumed Health Care Cost Trend Rates	The health care cost trend rate affects the projected benefit obligation. A 1% change in assumed health care cost growth rates would have effects shown in the following table.
		One-Percentage-				One-Percentage-
		Point Increase				Point Decrease
		(In Thousands)
	Effect on total of service and interest cost	$	134			$	(120	)
	Effect on post-retirement benefit obligation (a)	—				—
Schedule of Effect of Significant Unobservable Inputs, Changes in Plan Assets	The following table provides a reconciliation of pension plan assets measured at fair value using significant level 3 inputs for the years ended December 31, 2014 and 2013.
		Domestic				Alternative Investment				Real Estate				Total
		Equity Funds				Funds				Securities Fund
		(In Thousands)
	Balance as of December 31, 2013	$	22,488			$	39,171			$	24,022			$	85,681
	Actual gain (loss) on plan assets:
	Relating to assets still held at the reporting date	(154		)		1,970				2,630				4,446
	Relating to assets sold during the period	1,365				—				29				1,394
	Purchases, issuances and settlements, net	297				—				(242		)		55
	Balance as of December 31, 2014	$	23,996			$	41,141			$	26,439			$	91,576
	Balance as of December 31, 2012	$	18,493			$	45,535			$	20,927			$	84,955
	Actual gain (loss) on plan assets:
	Relating to assets still held at the reporting date	3,845				1,936				3,307				9,088
	Relating to assets sold during the period	—				826				—				826
	Purchases, issuances and settlements, net	150				(9,126		)		(212		)		(9,188		)
	Balance as of December 31, 2013	$	22,488			$	39,171			$	24,022			$	85,681
Schedule of Expected Benefit Payments	Cash Flows
	The following table shows the expected cash flows for our pension and post-retirement benefit plans for future years.
	Expected Cash Flows		Pension Benefits								Post-retirement Benefits
			To/(From) Trust				(From)				To/(From) Trust				(From)
							Company Assets								Company Assets
			(In Millions)
	Expected contributions:
	2015		$	42							$	—
	Expected benefit payments:
	2015		$	(35.1	)		$	(2.8	)		$	(8.2	)		$	(0.2	)
	2016		(37.3		)		(2.8		)		(8.3		)		(0.2		)
	2017		(39.5		)		(2.8		)		(8.4		)		(0.2		)
	2018		(41.9		)		(2.7		)		(8.6		)		(0.2		)
	2019		(44.2		)		(2.7		)		(8.7		)		(0.2		)
	2020-2024		(257.8		)		(13.0		)		(43.5		)		(1.0		)
Wolf Creek [Member]
Wolf Creek Interim Pension And Post-Retirement Benefit Disclosure [Line Items]
Schedule Of Benefit Obligation Fair Value Of Plan Assets And Amounts Recognized In Balance Sheet	The following tables summarize the status of KGE's 47% share of the Wolf Creek pension and post-retirement benefit plans.
		Pension Benefits								Post-retirement Benefits
	As of December 31,	2014				2013				2014				2013
		(In Thousands)
	Change in Benefit Obligation:
	Benefit obligation, beginning of year	$	162,820			$	176,891			$	10,010			$	11,020
	Service cost	5,695				6,835				173				206
	Interest cost	8,469				7,562				464				413
	Plan participants’ contributions	—				—				766				696
	Benefits paid	(5,039		)		(4,349		)		(1,292		)		(1,022		)
	Actuarial (gains) losses	38,375				(24,119		)		(1,881		)		(1,303		)
	Benefit obligation, end of year	$	210,320			$	162,820			$	8,240			$	10,010
	Change in Plan Assets:
	Fair value of plan assets, beginning of year	$	114,734			$	98,051			$	17			$	13
	Actual return on plan assets	7,626				13,166				—				—
	Employer contributions	7,089				7,624				515				330
	Plan participants' contributions	—				—				766				696
	Benefits paid	(4,789		)		(4,107		)		(1,292		)		(1,022		)
	Fair value of plan assets, end of year	$	124,660			$	114,734			$	6			$	17
	Funded status, end of year	$	(85,660	)		$	(48,086	)		$	(8,234	)		$	(9,993	)
	Amounts Recognized in the Balance Sheets Consist of:
	Current liability	$	(247	)		$	(237	)		$	(575	)		$	(614	)
	Noncurrent liability	(85,413		)		(47,849		)		(7,659		)		(9,379		)
	Net amount recognized	$	(85,660	)		$	(48,086	)		$	(8,234	)		$	(9,993	)
	Amounts Recognized in Regulatory Assets Consist of:
	Net actuarial loss	$	65,049			$	29,203			$	29			$	2,076
	Prior service cost	559				617				—				—
	Net amount recognized	$	65,608			$	29,820			$	29			$	2,076
Schedule Of Benefit Obligations In Excess Of Fair Value Of Plan Assets And Assumptions Used For Benefit Obligation
		Pension Benefits								Post-retirement Benefits
	As of December 31,	2014				2013				2014				2013
		(Dollars in Thousands)
	Pension Plans With a Projected Benefit Obligation In Excess of Plan Assets:
	Projected benefit obligation	$	210,320			$	162,820			$	—			$	—
	Fair value of plan assets	124,660				114,734				—				—
	Pension Plans With an Accumulated Benefit Obligation In Excess of Plan Assets:
	Accumulated benefit obligation	$	179,228			$	137,459			$	—			$	—
	Fair value of plan assets	124,660				114,734				—				—
	Post-retirement Plans With an Accumulated Post-retirement Benefit Obligation In Excess of Plan Assets:
	Accumulated post-retirement benefit obligation	$	—			$	—			$	8,240			$	10,010
	Fair value of plan assets	—				—				6				16
	Weighted-Average Actuarial Assumptions used to Determine Net Periodic Benefit Obligation:
	Discount rate	4.2		%		5.11		%		3.89		%		4.7		%
	Compensation rate increase	4		%		4		%		—				—
Schedule Of Net Benefit Costs And Assumptions Used For Net Periodic Cost	Following is additional information regarding KGE's 47% share of the Wolf Creek pension and other post-retirement benefit plans.
		Pension Benefits												Post-retirement Benefits
	Year Ended December 31,	2014				2013				2012				2014				2013				2012
		(Dollars in Thousands)
	Components of Net Periodic Cost (Benefit):
	Service cost	$	5,695			$	6,835			$	6,062			$	173			$	206			$	191
	Interest cost	8,469				7,562				7,537				464				413				411
	Expected return on plan assets	(8,084		)		(7,373		)		(6,577		)		—				—				—
	Amortization of unrecognized:
	Transition obligation, net	—				—				—				—				—				57
	Prior service costs	58				58				6				—				—				—
	Actuarial loss, net	2,987				5,421				5,366				165				265				234
	Net periodic cost before regulatory adjustment	9,125				12,503				12,394				802				884				893
	Regulatory adjustment (a)	2,328				(641		)		(1,776		)		—				—				—
	Net periodic cost	$	11,453			$	11,862			$	10,618			$	802			$	884			$	893
	Other Changes in Plan Assets and Benefit Obligations Recognized in Regulatory Assets:
	Current year actuarial (gain) loss	$	38,833			$	(29,911	)		$	4,629			$	(1,881	)		$	(1,303	)		$	669
	Amortization of actuarial loss (gain)	(2,987		)		(5,421		)		(5,366		)		(165		)		(265		)		(234		)
	Current year prior service cost	—				—				650				—				—				—
	Amortization of prior service cost	(58		)		(58		)		(6		)		—				—				—
	Amortization of transition obligation	—				—				—				—				—				(57		)
	Total recognized in regulatory assets	$	35,788			$	(35,390	)		$	(93	)		$	(2,046	)		$	(1,568	)		$	378
	Total recognized in net periodic cost and regulatory assets	$	47,241			$	(23,528	)		$	10,525			$	(1,244	)		$	(684	)		$	1,271
	Weighted-Average Actuarial Assumptions used to Determine Net Periodic Cost:
	Discount rate	5.11		%		4.16		%		4.55		%		4.7		%		3.78		%		4.1		%
	Expected long-term return on plan assets	7.5		%		7.5		%		7.5		%		—				—				—
	Compensation rate increase	4		%		4		%		4		%		—				—				—
	_______________
	(a)	The regulatory adjustment represents the difference between current period pension or post-retirement benefit expense and the amount of such expense recognized in setting our prices.
Schedule Of Amounts To Be Amortized From Regulatory Assets To Net Periodic Cost	We estimate that we will amortize the following amounts from regulatory assets into net periodic cost in 2015.
		Pension				Post-retirement
		Benefits				Benefits
		(In Thousands)
	Actuarial loss	$	5,930			$	2
	Prior service cost	57				—
	Total	$	5,987			$	2
Schedule of Health Care Cost Trend Rates	For measurement purposes, the assumed annual health care cost growth rates were as follows.
		As of December 31,
		2014			2013
	Health care cost trend rate assumed for next year	7	%		7.5	%
	Rate to which the cost trend rate is assumed to decline (the ultimate trend rate)	5	%		5	%
	Year that the rate reaches the ultimate trend rate	2019			2019
Schedule of Effect of One-Percentage-Point Change in Assumed Health Care Cost Trend Rates	The health care cost trend rate affects the projected benefit obligation. A 1% change in assumed health care cost growth rates would have effects shown in the following table.
		One-Percentage-				One-Percentage-
		Point Increase				Point Decrease
		(In Thousands)
	Effect on total of service and interest cost	$	(8	)		$	8
	Effect on post-retirement benefit obligation	(111		)		113
Schedule of Allocation of Plan Assets	The following table provides the fair value of KGE's 47% share of Wolf Creek's pension plan assets and the corresponding level of hierarchy as of December 31, 2014 and 2013.
	As of December 31, 2014		Level 1				Level 2				Level 3				Total
			(In Thousands)
	Assets:
	Domestic equity funds		$	—			$	31,580			$	—			$	31,580
	International equity funds		—				38,624				—				38,624
	Core bond funds		—				31,854				—				31,854
	Real estate securities fund		—				6,313				5,649				11,962
	Commodities fund		—				5,887				—				5,887
	Alternative investment fund		—				—				4,309				4,309
	Cash equivalents		—				444				—				444
	Total Assets Measured at Fair Value		$	—			$	114,702			$	9,958			$	124,660
	As of December 31, 2013
	Assets:
	Domestic equity funds		$	—			$	30,599			$	—			$	30,599
	International equity funds		—				36,868				—				36,868
	Core bond funds		—				26,926				—				26,926
	Real estate securities fund		—				5,440				5,094				10,534
	Commodities fund		—				5,245				—				5,245
	Alternative investment fund		—				—				4,147				4,147
	Cash equivalents		—				415				—				415
	Total Assets Measured at Fair Value		$	—			$	105,493			$	9,241			$	114,734
Schedule of Effect of Significant Unobservable Inputs, Changes in Plan Assets	The following table provides a reconciliation of KGE's 47% share of Wolf Creek's pension plan assets measured at fair value using significant level 3 inputs for the years ended December 31, 2014 and 2013.
		Real Estate				Alternative Investment				Total
		Securities				Fund
		Fund
		(In Thousands)
	Balance as of December 31, 2013	$	5,094			$	4,147			$	9,241
	Actual gain on plan assets:
	Relating to assets still held at the reporting date	555				162				717
	Balance as of December 31, 2014	$	5,649			$	4,309			$	9,958
	Balance as of December 31, 2012	$	4,541			$	3,900			$	8,441
	Actual gain on plan assets:
	Relating to assets still held at the reporting date	553				247				800
	Balance as of December 31, 2013	$	5,094			$	4,147			$	9,241
Schedule of Expected Benefit Payments	The following table shows our expected cash flows for KGE's 47% share of Wolf Creek's pension and post-retirement benefit plans for future years.
	Expected Cash Flows		Pension Benefits								Post-retirement Benefits
			To/(From) Trust				(From)				To/(From) Trust				(From)
							Company Assets								Company Assets
			(In Millions)
	Expected contributions:
	2015		$	4.7							$	0.6
	Expected benefit payments:
	2015		$	(5.4	)		$	(0.2	)		$	(0.6	)		$	—
	2016		(6.1		)		(0.2		)		(0.6		)		—
	2017		(6.8		)		(0.2		)		(0.6		)		—
	2018		(7.5		)		(0.2		)		(0.6		)		—
	2019		(8.2		)		(0.2		)		(0.7		)		—
	2020 - 2024		(51.0		)		(1.1		)		(3.2		)		—

Commitments_And_Contingencies_

Commitments And Contingencies (Tables)	12 Months Ended
	Dec. 31, 2014
Commitments and Contingencies Disclosure [Abstract]
Committed Purchase Obligations Disclosure	The yearly detail of the aggregate amount of required payments as of December 31, 2014, was as follows.
		Committed
		Amount
		(In Thousands)
	2015	$	406,859
	2016	39,551
	2017	9,223
	Thereafter	27,247
	Total amount committed	$	482,880

Asset_Retirement_Obligations_T

Asset Retirement Obligations (Tables)	12 Months Ended
	Dec. 31, 2014
Asset Retirement Obligation [Abstract]
Schedule of Asset Retirement Obligations [Table Text Block]	The following table summarizes our legal AROs included on our consolidated balance sheets in long-term liabilities.
		As of December 31,
		2014			2013
		(In Thousands)
	Beginning ARO	$	160,682		$	152,648
	Increase in nuclear decommissioning ARO liability	50,683			—
	Increase in other ARO liabilities	9,580			—
	Liabilities settled	(593		)	(973		)
	Accretion expense	10,316			9,007
	Ending ARO	$	230,668		$	160,682

Common_and_Preferred_Stock_Tab

Common and Preferred Stock (Tables)	12 Months Ended
	Dec. 31, 2014
Schedule of Forward Contracts Indexed to Issuer's Equity [Abstract]
Financial Instruments Not Subject to Mandatory Redemption Disclosure [Table Text Block]	The table below shows the redemption amounts for all series of preferred stock.
	Rate		Shares		Principal			Call	Premium		Total
					Outstanding			Price			Cost
											to Redeem
	(Dollars in Thousands)
	4.50%		121,613		$	12,161		108.00%	$	973	$	13,134
	4.25%		54,970		5,497			101.50%	82		5,579
	5.00%		37,780		3,778			102.00%	76		3,854
			214,363		$	21,436			$	1,131	$	22,567
Schedule of Forward Contracts Indexed to Issuer's Equity [Table Text Block]	The following table summarizes our common stock activity pursuant to the three forward sale agreements.
		Year Ended December 31,
		2014		2013			2012
	Shares that could be settled at beginning of year	12,052,976		1,753,415			—
	Transactions entered	—		11,367,673			1,753,415
	Transactions settled (a)	2,892,476		1,068,112			—
	Shares that could be settled at end of year (b)	9,160,500		12,052,976			1,753,415
	_______________
	(a) The shares settled during the years ended December 31, 2014 and 2013, were settled with a physical settlement amount of approximately $82.9 million and $27.0 million, respectively.
	(b) Assuming physical share settlement of the 9.2 million shares associated with the forward sale transactions that could be settled as of December 31, 2014, Westar Energy would have received aggregate proceeds of approximately $258.3 million based on a weighted average forward price of $28.20 per share. In February 2015, Westar Energy settled 0.2 million shares with a physical settlement amount of approximately $7.5 million.

Variable_Interest_Entities_Tab

Variable Interest Entities (Tables)	12 Months Ended
	Dec. 31, 2014
Variable Interest Entities [Abstract]
Assets And Liabilities In Relation To VIEs	We have recorded the following assets and liabilities on our consolidated balance sheets related to the VIEs described above.
		As of December 31,
		2014		2013
		(In Thousands)
	Assets:
	Property, plant and equipment of variable interest entities, net	$	278,573	$	296,626
	Regulatory assets (a)	7,882		6,792
	Liabilities:
	Current maturities of long-term debt of variable interest entities	$	27,933	$	27,479
	Accrued interest (b)	2,961		3,472
	Long-term debt of variable interest entities, net	166,565		194,802
	_______________
	(a) Included in long-term regulatory assets on our consolidated balance sheets.
	(b) Included in accrued interest on our consolidated balance sheets.

Leases_Tables

Leases (Tables)	12 Months Ended
	Dec. 31, 2014
Leases [Abstract]
Operating Leases, Minimum Annual Rental Payments	Rental expense and estimated future commitments under operating leases are as follows.
	Year Ended December 31,		Total
			Operating
			Leases
			(In Thousands)
	Rental expense:
	2012		$	17,080
	2013		16,484
	2014		14,143
	Future commitments:
	2015		$	12,396
	2016		10,434
	2017		8,560
	2018		7,148
	2019		5,930
	Thereafter		9,115
	Total future commitments		$	53,583
Assets Recorded Under Capital Leases	Assets recorded under capital leases are listed below.
		As of December 31,
		2014				2013
		(In Thousands)
	Vehicles	$	18,819			$	12,141
	Computer equipment	1,504				1,758
	Generation plant	40,049				48,346
	Accumulated amortization	(11,741		)		(10,493		)
	Total capital leases	$	48,631			$	51,752
Capital Leases, Minimum Annual Rental Payments	Minimum annual rental payments, excluding administrative costs such as property taxes, insurance and maintenance, under capital leases are listed below.
	Year Ended December 31,		Total Capital
			Leases
			(In Thousands)
	2015		$	6,379
	2016		5,717
	2017		5,284
	2018		5,131
	2019		4,493
	Thereafter		59,660
			86,664
	Amounts representing imputed interest		(34,922		)
	Present value of net minimum lease payments under capital leases		51,742
	Less: Current portion		3,833
	Total long-term obligation under capital leases		$	47,909

Quarterly_Results_Unaudited_Ta

Quarterly Results (Unaudited) (Tables)	12 Months Ended
	Dec. 31, 2014
Quarterly Financial Information Disclosure [Abstract]
Schedule of Quarterly Financial Information	Our business is seasonal in nature and, in our opinion, comparisons between the quarters of a year do not give a true indication of overall trends and changes in operations.
	2014	First		Second		Third		Fourth
		(In Thousands, Except Per Share Amounts)
	Revenues (a)	$	628,556	$	612,668	$	764,040	$	596,439
	Net income (a)	70,970		55,822		149,760		45,773
	Net income attributable to Westar Energy, Inc. (a)	68,955		53,473		147,382		43,449
	Per Share Data (a):
	Basic:
	Earnings available	$	0.53	$	0.41	$	1.13	$	0.33
	Diluted:
	Earnings available	$	0.52	$	0.4	$	1.1	$	0.32
	Cash dividend declared per common share	$	0.35	$	0.35	$	0.35	$	0.35
	Market price per common share:
	High	$	35.33	$	38.24	$	38.23	$	43.15
	Low	$	31.67	$	34.51	$	33.76	$	33.73
	_______________
	(a)	Items are computed independently for each of the periods presented and the sum of the quarterly amounts may not equal the total for the year.
	2013	First		Second		Third		Fourth
		(In Thousands, Except Per Share Amounts)
	Revenues (a)	$	546,212	$	569,589	$	694,974	$	559,878
	Net income (a)	53,256		69,451		135,095		43,061
	Net income attributable to Westar Energy, Inc. (a)	51,144		67,188		133,125		41,062
	Per Share Data (a):
	Basic:
	Earnings available	$	0.4	$	0.53	$	1.04	$	0.32
	Diluted:
	Earnings available	$	0.4	$	0.52	$	1.04	$	0.32
	Cash dividend declared per common share	$	0.34	$	0.34	$	0.34	$	0.34
	Market price per common share:
	High	$	33.35	$	34.96	$	34.31	$	32.56
	Low	$	28.59	$	30.13	$	29.79	$	29.95
	_______________
	(a)	Items are computed independently for each of the periods presented and the sum of the quarterly amounts may not equal the total for the yea

Description_Of_Business_Detail

Description Of Business (Details)	12 Months Ended
	Dec. 31, 2014
	Customers
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Number of customers in Kansas	698,000

Summary_Of_Significant_Account3

Summary Of Significant Accounting Policies (Narrative) (Details) (USD $)	12 Months Ended
In Millions, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	Nov. 01, 2013	Oct. 31, 2012	Oct. 27, 2011
Property, Plant and Equipment [Line Items]
Estimated Increase In Annual Retail Revenues For Energy Efficiency Costs				$5	$1.30	$1.10
Average annual composite basis group depreciation rates	2.40%	2.50%	2.60%
Unbilled revenue	61	60.1
Nuclear Fuel [Member]
Property, Plant and Equipment [Line Items]
Accumulated amortization	72.3	46.2
Nuclear fuel charged to fuel and purchased power expense	$27.30	$26.50	28.3

Summary_Of_Significant_Account4

Summary Of Significant Accounting Policies (Fuel Inventory And Supplies) (Details) (USD $)	Dec. 31, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Public Utilities, Inventory [Line Items]
Total	$247,406	$239,511
Fuel Inventory [Member]
Public Utilities, Inventory [Line Items]
Public Utilitiy Inventory	70,416	78,368
Supplies [Member]
Public Utilities, Inventory [Line Items]
Public Utilitiy Inventory	$176,990	$161,143

Summary_Of_Significant_Account5

Summary Of Significant Accounting Policies (Allowance For Funds Used During Construction) (Details) (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Accounting Policies [Abstract]
Public Utilities, Allowance for Funds Used During Construction, Additions	$29,073	$25,849	$22,105
Allowance for Funds Used During Construction, Capitalized Interest	$12,044	$11,706	$10,399
Average AFUDC rates	6.70%	4.80%	5.00%

Summary_Of_Significant_Account6

Summary Of Significant Accounting Policies (Depreciable Lives of PP&E) (Details)	12 Months Ended
	Dec. 31, 2014
Minimum [Member]
Depreciable Lives [Line Items]
Transmission facilities, estimated useful life	15 years
Distribution facilities, estimated useful life	22 years
Other property, plant and equipment, estimated useful life	5 years
Maximum [Member]
Depreciable Lives [Line Items]
Transmission facilities, estimated useful life	75 years
Distribution facilities, estimated useful life	68 years
Other property, plant and equipment, estimated useful life	30 years
Fossil Fuel Plant [Member] | Minimum [Member]
Depreciable Lives [Line Items]
Generating facilities, estimated useful life	6 years
Fossil Fuel Plant [Member] | Maximum [Member]
Depreciable Lives [Line Items]
Generating facilities, estimated useful life	78 years
Nuclear Plant [Member] | Minimum [Member]
Depreciable Lives [Line Items]
Generating facilities, estimated useful life	55 years
Nuclear Plant [Member] | Maximum [Member]
Depreciable Lives [Line Items]
Generating facilities, estimated useful life	71 years
Other Plant in Service [Member] | Minimum [Member]
Depreciable Lives [Line Items]
Generating facilities, estimated useful life	19 years
Other Plant in Service [Member] | Maximum [Member]
Depreciable Lives [Line Items]
Generating facilities, estimated useful life	20 years

Summary_Of_Significant_Account7

Summary Of Significant Accounting Policies (Cash Surrender Value of Life Insurance) (Details) (USD $)	Dec. 31, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Accounting Policies [Abstract]
Cash surrender value of policies	$1,306,777	$1,289,457
Borrowings against policies	-1,173,956	-1,156,341
Corporate-owned life insurance, net	$132,821	$133,116

Summary_Of_Significant_Account8

Summary Of Significant Accounting Policies (Reconciliation Of Basic And Diluted EPS) (Details) (USD $)	3 Months Ended																12 Months Ended
In Thousands, except Share data, unless otherwise specified	Dec. 31, 2014		Sep. 30, 2014		Jun. 30, 2014		Mar. 31, 2014		Dec. 31, 2013		Sep. 30, 2013		Jun. 30, 2013		Mar. 31, 2013		Dec. 31, 2014		Dec. 31, 2013		Dec. 31, 2012
Accounting Policies [Abstract]
Net income																	$322,325		$300,863		$282,462
Less: Net income attributable to noncontrolling interests																	9,066		8,343		7,316
Net income attributable to Westar Energy, Inc.																	313,259		292,520		275,146
Less: Preferred dividends																	0		0		1,616
Participating Securities, Distributed and Undistributed Earnings (Loss), Diluted																	790		810		778
Net income allocated to common stock																	$312,469		$291,710		$272,752
Weighted average equivalent common shares outstanding - basic																	130,014,941		127,462,994		126,711,869
RSUs																	181,397		17,195		97,757
Forward sale agreements																	2,628,187		818,505		89,160
Weighted average equivalent common shares outstanding - diluted																	132,824,525	[1]	128,298,694	[1]	126,898,786	[1]
Basic earnings per common share	$0.33	[2]	$1.13	[2]	$0.41	[2]	$0.53	[2]	$0.32	[2]	$1.04	[2]	$0.53	[2]	$0.40	[2]	$2.40		$2.29		$2.15
Diluted earnings per common share	$0.32	[2]	$1.10	[2]	$0.40	[2]	$0.52	[2]	$0.32	[2]	$1.04	[2]	$0.52	[2]	$0.40	[2]	$2.35		$2.27		$2.15
Antidilutive shares																	0		0		0
[1]	(a)For the years ended December 31, 2014, 2013 and 2012, we had no antidilutive securities.
[2]	(a)Items are computed independently for each of the periods presented and the sum of the quarterly amounts may not equal the total for the year.

Summary_Of_Significant_Account9

Summary Of Significant Accounting Policies (Supplemental Cash Flow Information) (Details) (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Cash Paid For (Received From)
Interest on financing activities	$160,292	$148,691	$143,564
Income taxes, net of refunds	458	-11	-4,378
Noncash Investing and Financing Transactions
Property, plant and equipment additions	143,192	127,544	89,354
Issuance of common stock for reinvested dividends and compensation plans	9,155	9,641	9,089
Assets acquired through capital leases	8,717	334	10,683
Variable Interest Entity, Primary Beneficiary [Member]
Cash Paid For (Received From)
Interest on financing activities	12,183	13,892	16,214
Noncash Investing and Financing Transactions
Property, plant and equipment additions	-7,342	-14,282	0
Debt of VIEs	($7,342)	($14,282)	$0

Rate_Matters_And_Regulation_Re

Rate Matters And Regulation (Regulatory Assets and Liabilities) (Details) (USD $)	Dec. 31, 2014	Dec. 31, 2013
Regulatory Assets and Liabilities [Line Items]
Regulatory Assets	$859,778,000	$755,414,000
Regulatory Liabilities	343,485,000	329,556,000
Removal Costs [Member]
Regulatory Assets and Liabilities [Line Items]
Regulatory Liabilities	88,242,000	114,148,000
Deferred Regulatory Gain From Sale Leaseback [Member]
Regulatory Assets and Liabilities [Line Items]
Regulatory Liabilities	81,055,000	86,551,000
Nuclear Decommissioning [Member]
Regulatory Assets and Liabilities [Line Items]
Regulatory Liabilities	43,641,000	43,272,000
Retail Energy Cost Adjustment [Member]
Regulatory Assets and Liabilities [Line Items]
Regulatory Liabilities	33,274,000	15,414,000
Kansas Tax Credits [Member]
Regulatory Assets and Liabilities [Line Items]
Regulatory Liabilities	12,725,000	11,076,000
jurisdictional allowance for funds used during construction [Member]
Regulatory Assets and Liabilities [Line Items]
Regulatory Liabilities	33,103,000	7,893,000
Dismantling Costs [Member]
Regulatory Assets and Liabilities [Line Items]
Regulatory Liabilities	22,918,000	20,505,000
Gain on Sale of Oil [Member]
Regulatory Assets and Liabilities [Line Items]
Regulatory Liabilities	2,337,000	4,278,000
Other Post-retirement Benefit Costs [Member]
Regulatory Assets and Liabilities [Line Items]
Regulatory Liabilities	15,473,000	19,000,000
Fuel Supply and Electricity Contracts [Member]
Regulatory Assets and Liabilities [Line Items]
Regulatory Liabilities	1,738,000	2,635,000
Other Regulatory Liabilities [Member]
Regulatory Assets and Liabilities [Line Items]
Regulatory Liabilities	8,979,000	4,784,000
Other Pension Plans, Postretirement or Supplemental Plans, Defined Benefit [Member]
Regulatory Assets and Liabilities [Line Items]
Regulatory Assets	399,800,000
Pension Cost [Member]
Regulatory Assets and Liabilities [Line Items]
Regulatory Assets	35,800,000
Deferred Employee Benefit Costs Amortization Expense, Next Twelve Months	9,800,000
Deferred Employee Benefit Costs [Member]
Regulatory Assets and Liabilities [Line Items]
Regulatory Assets	435,590,000	277,122,000
Deferred Employee Benefit Costs Amortization Expense, Next Twelve Months	39,500,000
Amounts Due From Customers For Future Income Taxes, Net [Member]
Regulatory Assets and Liabilities [Line Items]
Regulatory Assets	153,984,000	163,742,000
Depreciation [Member]
Regulatory Assets and Liabilities [Line Items]
Regulatory Assets	68,422,000	71,047,000
Debt Reacquisition Costs [Member]
Regulatory Assets and Liabilities [Line Items]
Regulatory Assets	61,079,000	63,882,000
Asset Retirement Obligation [Member]
Regulatory Assets and Liabilities [Line Items]
Regulatory Assets	26,106,000	23,555,000
Ad Valorem Tax [Member]
Regulatory Assets and Liabilities [Line Items]
Regulatory Assets	39,428,000	34,492,000
Energy Efficiency Program Costs [Member]
Regulatory Assets and Liabilities [Line Items]
Regulatory Assets	8,933,000	14,477,000
Disallowed Plant Costs [Member]
Regulatory Assets and Liabilities [Line Items]
Regulatory Assets	15,809,000	15,964,000
Cash Flow Hedging [Member]
Regulatory Assets and Liabilities [Line Items]
Regulatory Assets		27,594,000
Retail Energy Cost Adjustment [Member]
Regulatory Assets and Liabilities [Line Items]
Regulatory Assets	0	22,138,000
Nuclear Refueling [Member]
Regulatory Assets and Liabilities [Line Items]
Regulatory Assets	11,165,000	29,026,000
Other Regulatory Assets [Member]
Regulatory Assets and Liabilities [Line Items]
Regulatory Assets	12,648,000	12,375,000
Cash Flow Hedging [Member]
Regulatory Assets and Liabilities [Line Items]
Regulatory Assets	$26,614,000	$27,600,000

Rate_Matters_And_Regulation_Na

Rate Matters And Regulation (Narrative) (Details) (USD $)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	Nov. 01, 2013	Jun. 30, 2013	Mar. 01, 2013	Jan. 31, 2013	Oct. 31, 2012	Jun. 30, 2012	Apr. 30, 2012	Jan. 31, 2012	Oct. 27, 2011	Jun. 30, 2011	Apr. 01, 2011	Jan. 31, 2011
Regulatory Assets and Liabilities [Line Items]
Regulatory Liabilities	$343,485,000	$329,556,000
Depreciation, Amortization and Accretion, Net	286,442,000	272,593,000	270,464,000
Change in Depreciation Estimate		43,600,000
Environmental Upgrades of Jointly Owned Utility Plant			1,200,000,000
Entity Share of Environmental Upgrades of Jointly Owned Plant	610,000,000
Estimated Increase In Annual Retail Revenues For Environmental Costs					11,000,000				27,300,000				19,500,000
Proposed Increase In Annual Retail Revenues	4,000,000	30,700,000	50,000,000
Estimated Increase In Annual Retail Revenues For Transmission Costs						41,000,000				11,800,000				36,700,000
Estimated Increase In Annual Retail Revenues For Energy Efficiency Costs				5,000,000				1,300,000				1,100,000
Estimated Increase In Annual Revenues For Property Tax							12,700,000				15,200,000				5,900,000
Estimated Increase In Annual Transmission Revenues	44,300,000	12,200,000	38,200,000
La Cygne Generating Station [Member]
Regulatory Assets and Liabilities [Line Items]
Ownership Percentage	50.00%
Retail Energy Cost Adjustment [Member]
Regulatory Assets and Liabilities [Line Items]
Regulatory Liabilities	33,274,000	15,414,000
Regulatory Liability, Amortization Period	1
Postretirement Benefit Costs [Member]
Regulatory Assets and Liabilities [Line Items]
Regulatory Liabilities	15,473,000	19,000,000
Regulatory Liability, Amortization Period	5
Gain on Sale of Oil [Member]
Regulatory Assets and Liabilities [Line Items]
Regulatory Liabilities	2,337,000	4,278,000
Regulatory Liability, Amortization Period	3
Pension Cost [Member]
Regulatory Assets and Liabilities [Line Items]
Deferred Employee Benefit Costs Amortization Expense, Next Twelve Months	9,800,000
Regulatory Asset, Amortization Period	5
Deferred Employee Benefit Costs [Member]
Regulatory Assets and Liabilities [Line Items]
Deferred Employee Benefit Costs Amortization Expense, Next Twelve Months	39,500,000
Ad Valorem Tax [Member]
Regulatory Assets and Liabilities [Line Items]
Regulatory Asset, Amortization Period	1
Energy Efficiency Program Costs [Member]
Regulatory Assets and Liabilities [Line Items]
Regulatory Asset, Amortization Period	1
Retail Energy Cost Adjustment [Member]
Regulatory Assets and Liabilities [Line Items]
Regulatory Asset, Amortization Period	1
Regulatory Assets Increase [Member]
Regulatory Assets and Liabilities [Line Items]
Depreciation, Amortization and Accretion, Net	$20,000,000

Financial_Instruments_and_Trad2

Financial Instruments and Trading Securities (Narrative) (Details) (USD $)	12 Months Ended		0 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Jan. 20, 2012	Dec. 31, 2012
Derivative Instruments, Gain (Loss) [Line Items]
Revised ARO estimate	$9,580,000	$0
Derivative Liability, Notional Amount				125,000,000
Regulatory Assets	859,778,000	755,414,000
Cash Flow Hedging [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Interest rate cash flow hedge settlement cost			29,700,000
Regulatory Assets	$26,614,000	$27,600,000

Financial_Instruments_and_Trad3

Financial Instruments and Trading Securities (Carrying Values And Fair Values Of Financial Instruments) (Details) (USD $)	Dec. 31, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Debt Instrument [Line Items]
Carrying Value	$3,226,940	$3,224,440
Fixed Rate Debt Member
Debt Instrument [Line Items]
Carrying Value	3,105,000	3,102,500
Fair Value	3,488,410	3,294,209
Fixed Rate Debt Of Variable Interest Entities [Member]
Debt Instrument [Line Items]
Carrying Value	194,204	221,682
Fair Value	$213,579	$241,241

Financial_Instruments_and_Trad4

Financial Instruments and Trading Securities (Fair Value Of Assets And Liabilities) (Details) (USD $)	Dec. 31, 2014		Dec. 31, 2013
In Thousands, unless otherwise specified
Financial And Derivative Instruments, Trading Securities, Energy Marketing And Risk Management [Line Items]
Total Nuclear Decommissioning Trust	$185,016		$175,625
Total Trading Securities, Assets	35,497	[1]	34,926
Total Assets Measured at Fair Value	220,513		210,551
Level 1 [Member]
Financial And Derivative Instruments, Trading Securities, Energy Marketing And Risk Management [Line Items]
Total Nuclear Decommissioning Trust	340		2
Total Trading Securities, Assets	168	[1]	166
Total Assets Measured at Fair Value	508		168
Level 2 [Member]
Financial And Derivative Instruments, Trading Securities, Energy Marketing And Risk Management [Line Items]
Total Nuclear Decommissioning Trust	152,111		145,620
Total Trading Securities, Assets	35,329	[1]	34,760
Total Assets Measured at Fair Value	187,440		180,380
Fair Value, Inputs, Level 3 [Member]
Financial And Derivative Instruments, Trading Securities, Energy Marketing And Risk Management [Line Items]
Total Nuclear Decommissioning Trust	32,565		30,003
Total Trading Securities, Assets	0	[1]	0
Total Assets Measured at Fair Value	32,565		30,003
Domestic Equity [Member]
Financial And Derivative Instruments, Trading Securities, Energy Marketing And Risk Management [Line Items]
Total Nuclear Decommissioning Trust	60,972		55,774
Total Trading Securities, Assets	18,698	[1]	18,075
Domestic Equity [Member] | Level 1 [Member]
Financial And Derivative Instruments, Trading Securities, Energy Marketing And Risk Management [Line Items]
Total Nuclear Decommissioning Trust	0		0
Total Trading Securities, Assets	0	[1]	0
Domestic Equity [Member] | Level 2 [Member]
Financial And Derivative Instruments, Trading Securities, Energy Marketing And Risk Management [Line Items]
Total Nuclear Decommissioning Trust	54,925		49,957
Total Trading Securities, Assets	18,698	[1]	18,075
Domestic Equity [Member] | Fair Value, Inputs, Level 3 [Member]
Financial And Derivative Instruments, Trading Securities, Energy Marketing And Risk Management [Line Items]
Total Nuclear Decommissioning Trust	6,047		5,817
Total Trading Securities, Assets	0	[1]	0
International Equity [Member]
Financial And Derivative Instruments, Trading Securities, Energy Marketing And Risk Management [Line Items]
Total Nuclear Decommissioning Trust	30,791		31,816
Total Trading Securities, Assets	4,252	[1]	4,519
International Equity [Member] | Level 1 [Member]
Financial And Derivative Instruments, Trading Securities, Energy Marketing And Risk Management [Line Items]
Total Nuclear Decommissioning Trust	0		0
Total Trading Securities, Assets	0	[1]	0
International Equity [Member] | Level 2 [Member]
Financial And Derivative Instruments, Trading Securities, Energy Marketing And Risk Management [Line Items]
Total Nuclear Decommissioning Trust	30,791		31,816
Total Trading Securities, Assets	4,252	[1]	4,519
International Equity [Member] | Fair Value, Inputs, Level 3 [Member]
Financial And Derivative Instruments, Trading Securities, Energy Marketing And Risk Management [Line Items]
Total Nuclear Decommissioning Trust	0		0
Total Trading Securities, Assets	0	[1]	0
Core Bonds [Member]
Financial And Derivative Instruments, Trading Securities, Energy Marketing And Risk Management [Line Items]
Total Nuclear Decommissioning Trust	19,289		18,107
Total Trading Securities, Assets	12,379	[1]	12,166
Core Bonds [Member] | Level 1 [Member]
Financial And Derivative Instruments, Trading Securities, Energy Marketing And Risk Management [Line Items]
Total Nuclear Decommissioning Trust	0		0
Total Trading Securities, Assets	0	[1]	0
Core Bonds [Member] | Level 2 [Member]
Financial And Derivative Instruments, Trading Securities, Energy Marketing And Risk Management [Line Items]
Total Nuclear Decommissioning Trust	19,289		18,107
Total Trading Securities, Assets	12,379	[1]	12,166
Core Bonds [Member] | Fair Value, Inputs, Level 3 [Member]
Financial And Derivative Instruments, Trading Securities, Energy Marketing And Risk Management [Line Items]
Total Nuclear Decommissioning Trust	0		0
Total Trading Securities, Assets	0	[1]	0
High-Yield Bonds [Member]
Financial And Derivative Instruments, Trading Securities, Energy Marketing And Risk Management [Line Items]
Total Nuclear Decommissioning Trust	13,198		12,902
High-Yield Bonds [Member] | Level 1 [Member]
Financial And Derivative Instruments, Trading Securities, Energy Marketing And Risk Management [Line Items]
Total Nuclear Decommissioning Trust	0		0
High-Yield Bonds [Member] | Level 2 [Member]
Financial And Derivative Instruments, Trading Securities, Energy Marketing And Risk Management [Line Items]
Total Nuclear Decommissioning Trust	13,198		12,902
High-Yield Bonds [Member] | Fair Value, Inputs, Level 3 [Member]
Financial And Derivative Instruments, Trading Securities, Energy Marketing And Risk Management [Line Items]
Total Nuclear Decommissioning Trust	0		0
Emerging Market Bonds [Member]
Financial And Derivative Instruments, Trading Securities, Energy Marketing And Risk Management [Line Items]
Total Nuclear Decommissioning Trust	10,988		11,055
Emerging Market Bonds [Member] | Level 1 [Member]
Financial And Derivative Instruments, Trading Securities, Energy Marketing And Risk Management [Line Items]
Total Nuclear Decommissioning Trust			0
Emerging Market Bonds [Member] | Level 2 [Member]
Financial And Derivative Instruments, Trading Securities, Energy Marketing And Risk Management [Line Items]
Total Nuclear Decommissioning Trust	10,988		11,055
Emerging Market Bonds [Member] | Fair Value, Inputs, Level 3 [Member]
Financial And Derivative Instruments, Trading Securities, Energy Marketing And Risk Management [Line Items]
Total Nuclear Decommissioning Trust			0
Other Fixed Income [Member]
Financial And Derivative Instruments, Trading Securities, Energy Marketing And Risk Management [Line Items]
Total Nuclear Decommissioning Trust	4,779		4,690
Other Fixed Income [Member] | Level 1 [Member]
Financial And Derivative Instruments, Trading Securities, Energy Marketing And Risk Management [Line Items]
Total Nuclear Decommissioning Trust	0		0
Other Fixed Income [Member] | Level 2 [Member]
Financial And Derivative Instruments, Trading Securities, Energy Marketing And Risk Management [Line Items]
Total Nuclear Decommissioning Trust	4,779		4,690
Other Fixed Income [Member] | Fair Value, Inputs, Level 3 [Member]
Financial And Derivative Instruments, Trading Securities, Energy Marketing And Risk Management [Line Items]
Total Nuclear Decommissioning Trust	0		0
Combination Debt and Equity Fund [Member]
Financial And Derivative Instruments, Trading Securities, Energy Marketing And Risk Management [Line Items]
Total Nuclear Decommissioning Trust	18,141		17,093
Combination Debt and Equity Fund [Member] | Level 1 [Member]
Financial And Derivative Instruments, Trading Securities, Energy Marketing And Risk Management [Line Items]
Total Nuclear Decommissioning Trust	0		0
Combination Debt and Equity Fund [Member] | Level 2 [Member]
Financial And Derivative Instruments, Trading Securities, Energy Marketing And Risk Management [Line Items]
Total Nuclear Decommissioning Trust	18,141		17,093
Combination Debt and Equity Fund [Member] | Fair Value, Inputs, Level 3 [Member]
Financial And Derivative Instruments, Trading Securities, Energy Marketing And Risk Management [Line Items]
Total Nuclear Decommissioning Trust	0		0
Alternative Investments [Member]
Financial And Derivative Instruments, Trading Securities, Energy Marketing And Risk Management [Line Items]
Total Nuclear Decommissioning Trust	16,970		15,675
Alternative Investments [Member] | Level 1 [Member]
Financial And Derivative Instruments, Trading Securities, Energy Marketing And Risk Management [Line Items]
Total Nuclear Decommissioning Trust	0		0
Alternative Investments [Member] | Level 2 [Member]
Financial And Derivative Instruments, Trading Securities, Energy Marketing And Risk Management [Line Items]
Total Nuclear Decommissioning Trust	0		0
Alternative Investments [Member] | Fair Value, Inputs, Level 3 [Member]
Financial And Derivative Instruments, Trading Securities, Energy Marketing And Risk Management [Line Items]
Total Nuclear Decommissioning Trust	16,970		15,675
Real Estate Securities [Member]
Financial And Derivative Instruments, Trading Securities, Energy Marketing And Risk Management [Line Items]
Total Nuclear Decommissioning Trust	9,548		8,511
Real Estate Securities [Member] | Level 1 [Member]
Financial And Derivative Instruments, Trading Securities, Energy Marketing And Risk Management [Line Items]
Total Nuclear Decommissioning Trust	0		0
Real Estate Securities [Member] | Level 2 [Member]
Financial And Derivative Instruments, Trading Securities, Energy Marketing And Risk Management [Line Items]
Total Nuclear Decommissioning Trust	0		0
Real Estate Securities [Member] | Fair Value, Inputs, Level 3 [Member]
Financial And Derivative Instruments, Trading Securities, Energy Marketing And Risk Management [Line Items]
Total Nuclear Decommissioning Trust	9,548		8,511
Cash Equivalents [Member]
Financial And Derivative Instruments, Trading Securities, Energy Marketing And Risk Management [Line Items]
Total Nuclear Decommissioning Trust	340		2
Total Trading Securities, Assets	168	[1]	166
Cash Equivalents [Member] | Level 1 [Member]
Financial And Derivative Instruments, Trading Securities, Energy Marketing And Risk Management [Line Items]
Total Nuclear Decommissioning Trust	340		2
Total Trading Securities, Assets	168	[1]	166
Cash Equivalents [Member] | Level 2 [Member]
Financial And Derivative Instruments, Trading Securities, Energy Marketing And Risk Management [Line Items]
Total Nuclear Decommissioning Trust	0		0
Total Trading Securities, Assets	0	[1]	0
Cash Equivalents [Member] | Fair Value, Inputs, Level 3 [Member]
Financial And Derivative Instruments, Trading Securities, Energy Marketing And Risk Management [Line Items]
Total Nuclear Decommissioning Trust	0		0
Total Trading Securities, Assets	$0	[1]	$0
[1]	{F|ahBzfndlYmZpbGluZ3MtaHJkcmoLEgZYTUxEb2MiXlhCUkxEb2NHZW5JbmZvOmM4NjllMjVjOGIzYzQ1YzlhZDY3NWJiMmY0MWQ3MmQ3fFRleHRTZWxlY3Rpb246QTBGQTIzQUNGRjQwQjQ0MjlGQUNCM0UyNTU3OEY2QjgM}

Financial_Instruments_and_Trad5

Financial Instruments and Trading Securities (Reconciliations Of Assets And Liabilities At Fair Value) (Details) (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]
Balance at period start	$30,003	$12,764
Regulatory liabilities	2,723	2,261
Purchases	686	15,628
Sales	-847	-650
Balance at period end	32,565	30,003
Domestic Equity [Member]
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]
Balance at period start	5,817	4,899
Regulatory liabilities	391	940
Purchases	335	341
Sales	-496	-363
Balance at period end	6,047	5,817
Alternative Investments [Member]
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]
Balance at period start	15,675	0
Regulatory liabilities	1,295	675
Purchases	0	15,000
Sales	0	0
Balance at period end	16,970	15,675
Real Estate Securities [Member]
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]
Balance at period start	8,511	7,865
Regulatory liabilities	1,037	646
Purchases	351	287
Sales	-351	-287
Balance at period end	$9,548	$8,511

Financial_Instruments_and_Trad6

Financial Instruments and Trading Securities (Unrealized Gains And Losses On Financial Statements) (Details) (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]
Regulatory liabilities	$1,876	$1,611
Domestic Equity [Member]
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]
Regulatory liabilities	-105	577
Alternative Investments [Member]
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]
Regulatory liabilities	1,296	675
Real Estate Securities [Member]
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]
Regulatory liabilities	$685	$359

Financial_Instruments_and_Trad7

Financial Instruments and Trading Securities (Investments In Financial Instruments) (Details) (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2014		Dec. 31, 2013
Financial And Derivative Instruments, Trading Securities, Energy Marketing And Risk Management [Line Items]
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share, Redemption Restriction Period	15 years
Total Nuclear Decommissioning Trust	$185,016		$175,625
Total Trading Securities, Assets	35,497	[1]	34,926
Total	220,513		210,551
Alternative Investments [Member]
Financial And Derivative Instruments, Trading Securities, Energy Marketing And Risk Management [Line Items]
Total Nuclear Decommissioning Trust	16,970		15,675
Real Estate Securities [Member]
Financial And Derivative Instruments, Trading Securities, Energy Marketing And Risk Management [Line Items]
Total Nuclear Decommissioning Trust	9,548		8,511
International Equity [Member]
Financial And Derivative Instruments, Trading Securities, Energy Marketing And Risk Management [Line Items]
Total Nuclear Decommissioning Trust	30,791		31,816
Total Trading Securities, Assets	4,252	[1]	4,519
Core Bonds [Member]
Financial And Derivative Instruments, Trading Securities, Energy Marketing And Risk Management [Line Items]
Total Nuclear Decommissioning Trust	19,289		18,107
Total Trading Securities, Assets	12,379	[1]	12,166
Domestic Equity [Member]
Financial And Derivative Instruments, Trading Securities, Energy Marketing And Risk Management [Line Items]
Total Nuclear Decommissioning Trust	60,972		55,774
Total Trading Securities, Assets	18,698	[1]	18,075
Fair Value [Member]
Financial And Derivative Instruments, Trading Securities, Energy Marketing And Risk Management [Line Items]
Total Nuclear Decommissioning Trust	32,565		30,003
Total Trading Securities, Assets	35,329		34,760
Total	67,894		64,763
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share, Unfunded Commitments	2,348		2,683
Fair Value [Member] | Alternative Investments [Member]
Financial And Derivative Instruments, Trading Securities, Energy Marketing And Risk Management [Line Items]
Total Nuclear Decommissioning Trust	16,970		15,675
Fair Value [Member] | Real Estate Securities [Member]
Financial And Derivative Instruments, Trading Securities, Energy Marketing And Risk Management [Line Items]
Total Nuclear Decommissioning Trust	9,548		8,511
Fair Value [Member] | International Equity [Member]
Financial And Derivative Instruments, Trading Securities, Energy Marketing And Risk Management [Line Items]
Total Trading Securities, Assets	4,252		4,519
Fair Value [Member] | Core Bonds [Member]
Financial And Derivative Instruments, Trading Securities, Energy Marketing And Risk Management [Line Items]
Total Trading Securities, Assets	12,379		12,166
Fair Value [Member] | Domestic Equity [Member]
Financial And Derivative Instruments, Trading Securities, Energy Marketing And Risk Management [Line Items]
Total Nuclear Decommissioning Trust	6,047		5,817
Total Trading Securities, Assets	18,698		18,075
Decommissioning Trust Assets [Member] | Fair Value [Member]
Financial And Derivative Instruments, Trading Securities, Energy Marketing And Risk Management [Line Items]
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share, Unfunded Commitments	2,348		2,683
Decommissioning Trust Assets [Member] | Fair Value [Member] | Alternative Investments [Member]
Financial And Derivative Instruments, Trading Securities, Energy Marketing And Risk Management [Line Items]
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share, Unfunded Commitments	0		0
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share, Investment Redemption, Frequency	quarterly
Decommissioning Trust Assets [Member] | Fair Value [Member] | Real Estate Securities [Member]
Financial And Derivative Instruments, Trading Securities, Energy Marketing And Risk Management [Line Items]
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share, Unfunded Commitments	0		0
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share, Investment Redemption, Frequency	Quarterly
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share, Investment Redemption, Notice Period	80 days
Decommissioning Trust Assets [Member] | Fair Value [Member] | Domestic Equity [Member]
Financial And Derivative Instruments, Trading Securities, Energy Marketing And Risk Management [Line Items]
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share, Unfunded Commitments	2,348		2,683
Trading Securities [Member] | Fair Value [Member]
Financial And Derivative Instruments, Trading Securities, Energy Marketing And Risk Management [Line Items]
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share, Unfunded Commitments	0		0
Trading Securities [Member] | Fair Value [Member] | International Equity [Member]
Financial And Derivative Instruments, Trading Securities, Energy Marketing And Risk Management [Line Items]
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share, Unfunded Commitments	0		0
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share, Investment Redemption, Frequency	Upon Notice
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share, Investment Redemption, Notice Period	1 day
Trading Securities [Member] | Fair Value [Member] | Core Bonds [Member]
Financial And Derivative Instruments, Trading Securities, Energy Marketing And Risk Management [Line Items]
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share, Unfunded Commitments	0		0
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share, Investment Redemption, Frequency	Upon Notice
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share, Investment Redemption, Notice Period	1 day
Trading Securities [Member] | Fair Value [Member] | Domestic Equity [Member]
Financial And Derivative Instruments, Trading Securities, Energy Marketing And Risk Management [Line Items]
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share, Unfunded Commitments	$0		$0
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share, Investment Redemption, Frequency	Upon Notice
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share, Investment Redemption, Notice Period	1 day
[1]	{F|ahBzfndlYmZpbGluZ3MtaHJkcmoLEgZYTUxEb2MiXlhCUkxEb2NHZW5JbmZvOmM4NjllMjVjOGIzYzQ1YzlhZDY3NWJiMmY0MWQ3MmQ3fFRleHRTZWxlY3Rpb246QTBGQTIzQUNGRjQwQjQ0MjlGQUNCM0UyNTU3OEY2QjgM}

Financial_Instruments_and_Trad8

Financial Instruments and Trading Securities (Changes In The Fair Value Of Commodity Derivative Instruments) (Details) (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013
Financial And Derivative Instruments, Trading Securities, Energy Marketing And Risk Management [Line Items]
Asset Retirement Obligation, Revision of Estimate	$9,580	$0

Financial_Investments_Narrativ

Financial Investments (Narrative) (Details) (USD $)	12 Months Ended
	Dec. 31, 2014		Dec. 31, 2013	Dec. 31, 2012
Schedule of Available-for-sale Securities [Line Items]
Total Trading Securities, Assets	$35,497,000	[1]	$34,926,000
Unrealized gains (losses) on trading securities	2,600,000		6,700,000	4,100,000
Realized gains (losses) on available-for-sale-securities	100,000		5,300,000	600,000
Supplemental Employee Retirement Plans, Defined Benefit [Member]
Schedule of Available-for-sale Securities [Line Items]
Benefit obligation for certain retirement benefits	$29,800,000		$27,000,000
[1]	{F|ahBzfndlYmZpbGluZ3MtaHJkcmoLEgZYTUxEb2MiXlhCUkxEb2NHZW5JbmZvOmM4NjllMjVjOGIzYzQ1YzlhZDY3NWJiMmY0MWQ3MmQ3fFRleHRTZWxlY3Rpb246QTBGQTIzQUNGRjQwQjQ0MjlGQUNCM0UyNTU3OEY2QjgM}

Financial_Investments_Cost_And

Financial Investments (Cost And Fair Value Of Available-For-Sale Securities) (Details) (USD $)	Dec. 31, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Schedule of Available-for-sale Securities [Line Items]
Cost	$164,088	$155,244
Gross Unrealized Gain	24,770	23,753
Gross Unrealized Loss	3,842	3,372
Fair Value	185,016	175,625
Allocation	100.00%	100.00%
Domestic Equity [Member]
Schedule of Available-for-sale Securities [Line Items]
Cost	46,126	40,976
Gross Unrealized Gain	14,853	14,799
Gross Unrealized Loss	7	1
Fair Value	60,972	55,774
Allocation	33.00%	32.00%
International Equity [Member]
Schedule of Available-for-sale Securities [Line Items]
Cost	27,521	26,581
Gross Unrealized Gain	3,683	5,266
Gross Unrealized Loss	413	31
Fair Value	30,791	31,816
Allocation	17.00%	18.00%
Core Bonds [Member]
Schedule of Available-for-sale Securities [Line Items]
Cost	18,811	18,287
Gross Unrealized Gain	478	0
Gross Unrealized Loss	0	180
Fair Value	19,289	18,107
Allocation	10.00%	10.00%
High-Yield Bonds [Member]
Schedule of Available-for-sale Securities [Line Items]
Cost	13,342	12,275
Gross Unrealized Gain	0	627
Gross Unrealized Loss	144	0
Fair Value	13,198	12,902
Allocation	7.00%	7.00%
Emerging Market Bonds [Member]
Schedule of Available-for-sale Securities [Line Items]
Cost	12,556	12,207
Gross Unrealized Gain	0	0
Gross Unrealized Loss	1,568	1,152
Fair Value	10,988	11,055
Allocation	6.00%	6.00%
Other Fixed Income [Member]
Schedule of Available-for-sale Securities [Line Items]
Cost	4,798	4,684
Gross Unrealized Gain	0	6
Gross Unrealized Loss	19	0
Fair Value	4,779	4,690
Allocation	3.00%	3.00%
Combination Debt and Equity Fund [Member]
Schedule of Available-for-sale Securities [Line Items]
Cost	14,975	14,964
Gross Unrealized Gain	3,786	2,380
Gross Unrealized Loss	620	251
Fair Value	18,141	17,093
Allocation	10.00%	10.00%
Alternative Investments [Member]
Schedule of Available-for-sale Securities [Line Items]
Cost	15,000	15,000
Gross Unrealized Gain	1,970	675
Gross Unrealized Loss	0	0
Fair Value	16,970	15,675
Allocation	9.00%	9.00%
Real Estate Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Cost	10,619	10,268
Gross Unrealized Gain	0	0
Gross Unrealized Loss	1,071	1,757
Fair Value	9,548	8,511
Allocation	5.00%	5.00%
Cash Equivalents [Member]
Schedule of Available-for-sale Securities [Line Items]
Cost	340	2
Gross Unrealized Gain	0	0
Gross Unrealized Loss	0	0
Fair Value	$340	$2

Financial_Investments_Fair_Val

Financial Investments (Fair Value And Gross Unrealized Losses Of Available-For-Sale Securities) (Details) (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013
Schedule of Available-for-sale Securities [Line Items]
Fair Value, Less than 12 Months	$23,882	$41,748
Gross Unrealized Losses, Less than 12 Months	-576	1,615
Fair Value, 12 Months or Greater	26,691	8,511
Gross Unrealized Losses, 12 Months or Greater	-3,266	1,757
Fair Value, Total	50,573	50,259
Gross Unrealized Losses, Total	3,842	-3,372
Domestic Equity [Member]
Schedule of Available-for-sale Securities [Line Items]
Fair Value, Less than 12 Months	0	59
Gross Unrealized Losses, Less than 12 Months	0	1
Fair Value, 12 Months or Greater	263	0
Gross Unrealized Losses, 12 Months or Greater	7	0
Fair Value, Total	263	59
Gross Unrealized Losses, Total	-7	-1
Combination Debt Equity And Other Fund [Member]
Schedule of Available-for-sale Securities [Line Items]
Fair Value, Less than 12 Months	0	6,283
Gross Unrealized Losses, Less than 12 Months	0	251
Fair Value, 12 Months or Greater	5,892	0
Gross Unrealized Losses, 12 Months or Greater	620	0
Fair Value, Total	5,892	6,283
Gross Unrealized Losses, Total	-620	-251
Real Estate [Member]
Schedule of Available-for-sale Securities [Line Items]
Fair Value, Less than 12 Months	0	0
Gross Unrealized Losses, Less than 12 Months	0	0
Fair Value, 12 Months or Greater	9,548	8,511
Gross Unrealized Losses, 12 Months or Greater	1,071	1,757
Fair Value, Total	9,548	8,511
Gross Unrealized Losses, Total	-1,071	-1,757
International Equity [Member]
Schedule of Available-for-sale Securities [Line Items]
Fair Value, Less than 12 Months	5,905	6,244
Gross Unrealized Losses, Less than 12 Months	413	31
Fair Value, 12 Months or Greater	0	0
Gross Unrealized Losses, 12 Months or Greater	0	0
Fair Value, Total	5,905	6,244
Gross Unrealized Losses, Total	-413	-31
High-Yield Bonds [Member]
Schedule of Available-for-sale Securities [Line Items]
Fair Value, Less than 12 Months	13,198
Gross Unrealized Losses, Less than 12 Months	144
Fair Value, 12 Months or Greater	0
Gross Unrealized Losses, 12 Months or Greater	0
Fair Value, Total	13,198
Gross Unrealized Losses, Total	-144
Core Bonds [Member]
Schedule of Available-for-sale Securities [Line Items]
Fair Value, Less than 12 Months		18,107
Gross Unrealized Losses, Less than 12 Months		180
Fair Value, 12 Months or Greater		0
Gross Unrealized Losses, 12 Months or Greater		0
Fair Value, Total		18,107
Gross Unrealized Losses, Total		-180
Emerging Market Bonds [Member]
Schedule of Available-for-sale Securities [Line Items]
Fair Value, Less than 12 Months	0	11,055
Gross Unrealized Losses, Less than 12 Months	0	1,152
Fair Value, 12 Months or Greater	10,988	0
Gross Unrealized Losses, 12 Months or Greater	1,568	0
Fair Value, Total	10,988	11,055
Gross Unrealized Losses, Total	-1,568	-1,152
Other Fixed Income [Member]
Schedule of Available-for-sale Securities [Line Items]
Fair Value, Less than 12 Months	4,779
Gross Unrealized Losses, Less than 12 Months	19
Fair Value, 12 Months or Greater	0
Gross Unrealized Losses, 12 Months or Greater	0
Fair Value, Total	4,779
Gross Unrealized Losses, Total	($19)

Property_Plant_And_Equipment_D

Property, Plant And Equipment (Details) (USD $)	Dec. 31, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Public Utility, Property, Plant and Equipment [Line Items]
Electric plant in service	$10,620,292	$9,753,787
Electric plant acquisition adjustment	-802,318	-802,318
Accumulated depreciation	-4,112,483	-3,971,735
Electric plant, net	7,310,127	6,584,370
Construction work in progress	773,144	904,586
Nuclear fuel, net	79,637	62,960
Property, plant and equipment, net	8,162,908	7,551,916
Variable Interest Entity [Member]
Public Utility, Property, Plant and Equipment [Line Items]
Electric plant in service	497,999	513,793
Accumulated depreciation	-219,426	-217,167
Property, plant and equipment, net	$278,573	$296,626

Property_Plant_And_Equipment_D1

Property, Plant And Equipment (Depreciation) (Details) (USD $)	12 Months Ended
In Millions, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Public Utility, Property, Plant and Equipment [Line Items]
Depreciation	$263.80	$249.90	$247.80
Variable Interest Entity [Member]
Public Utility, Property, Plant and Equipment [Line Items]
Depreciation	$9.70	$9.70	$9.80

Joint_Ownership_of_Utility_Pla2

Joint Ownership of Utility Plants Joint Ownership of Utility Plants (Details) (USD $)	12 Months Ended
	Dec. 31, 2014		Dec. 31, 2013
Jointly Owned Utility Plant, Net Ownership Amount [Abstract]
Investment	4,304,052,000
Accumulated Depreciation	1,689,781,000
Construction Work in Progress	459,385,000
Net Capacity, in MW	3,092
Ownership Percentage	47.00%
Accumulated Depreciation on VIE Investment in Property, Plant and Equipment	4,112,483,000		3,971,735,000
La Cygne unit 1 [Member]
Jointly Owned Utility Plant, Net Ownership Amount [Abstract]
Investment	345,866,000	[1]
Accumulated Depreciation	157,550,000	[1]
Construction Work in Progress	368,445,000	[1]
Net Capacity, in MW	367	[1]
Ownership Percentage	50.00%	[1]
JEC unit 1 [Member]
Jointly Owned Utility Plant, Net Ownership Amount [Abstract]
Investment	789,142,000	[1]
Accumulated Depreciation	189,973,000	[1]
Construction Work in Progress	11,150,000	[1]
Net Capacity, in MW	661	[1]
Ownership Percentage	92.00%	[1]
JEC unit 2 [Member]
Jointly Owned Utility Plant, Net Ownership Amount [Abstract]
Investment	540,871,000	[1]
Accumulated Depreciation	190,769,000	[1]
Construction Work in Progress	3,189,000	[1]
Net Capacity, in MW	658	[1]
Ownership Percentage	92.00%	[1]
JEC unit 3 [Member]
Jointly Owned Utility Plant, Net Ownership Amount [Abstract]
Investment	709,497,000	[1]
Accumulated Depreciation	309,540,000	[1]
Construction Work in Progress	3,246,000	[1]
Net Capacity, in MW	664	[1]
Ownership Percentage	92.00%	[1]
Wolf Creek [Member]
Jointly Owned Utility Plant, Net Ownership Amount [Abstract]
Investment	1,818,005,000	[2]
Accumulated Depreciation	788,602,000	[2]
Construction Work in Progress	73,333,000	[2]
Net Capacity, in MW	549	[1]
Ownership Percentage	47.00%	[2]
State Line [Member]
Jointly Owned Utility Plant, Net Ownership Amount [Abstract]
Investment	100,671,000	[3]
Accumulated Depreciation	53,347,000	[3]
Construction Work in Progress	22,000	[3]
Net Capacity, in MW	193	[3]
Ownership Percentage	40.00%	[3]
La Cygne unit 2 [Member]
Jointly Owned Utility Plant, Net Ownership Amount [Abstract]
Net Capacity, in MW	341	[3]
La Cygne Generating Station [Member]
Jointly Owned Utility Plant, Net Ownership Amount [Abstract]
Variable Interest Entity Percentage of Asset Held	50.00%
Jeffrey Energy Center [Member]
Jointly Owned Utility Plant, Net Ownership Amount [Abstract]
Variable Interest Entity Percentage of Asset Held	8.00%
Variable Interest Entity, Primary Beneficiary [Member]
Jointly Owned Utility Plant, Net Ownership Amount [Abstract]
Accumulated Depreciation on VIE Investment in Property, Plant and Equipment	219,426,000		217,167,000
Variable Interest Entity, Primary Beneficiary [Member] | La Cygne Generating Station [Member]
Jointly Owned Utility Plant, Net Ownership Amount [Abstract]
VIE Investment in Property, Plant and Equipment	392,100,000
Accumulated Depreciation on VIE Investment in Property, Plant and Equipment	194,500,000
[1]	Jointly owned with KCPL. Our 8% leasehold interest in Jeffrey Energy Center (JEC) that is consolidated as a VIE is reflected in the net megawatts (MW) and ownership percentage provided above, but not in the other amounts in the table.
[2]	Jointly owned with KCPL and Kansas Electric Power Cooperative, Inc.
[3]	Jointly owned with Empire District Electric Company.

ShortTerm_Debt_Details

Short-Term Debt (Details) (USD $)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	Sep. 01, 2014	Sep. 29, 2011	Feb. 01, 2014
Short-term Debt [Line Items]
Short-term debt amount outstanding	$257,600,000	$134,600,000
Weighted average amount outstanding	232,336,000	228,352,000
Weighted daily average interest rate, excluding fees	0.30%	0.39%
Interest expense on short-term debt	2,000,000	2,400,000	3,200,000
Commercial Paper and Revolving LIne of Credit [Member]
Short-term Debt [Line Items]
Short-Term Debt Maximum Borrowings	1,000,000,000
Weighted average interest rate	0.52%	0.28%
Commercial Paper [Member]
Short-term Debt [Line Items]
Short-Term Debt Maximum Borrowings	1,000,000,000
Commercial paper program, Maximim maturity period	365
Short-term debt amount outstanding	257,600,000	134,600,000
Revolving Credit Facility Lender One [Member]
Short-term Debt [Line Items]
Expected extended amount for line of credit					1,000,000,000
Line of credit facility expiration date	29-Sep-18
Line of Credit Facility, Increase(Decrease) in Maximum Borrowing Capacity				81,400,000
Issued letters of credit	15,600,000	18,400,000
Secured revolving credit facility				730,000,000
Secured revolving credit facility borrowed	0	0
Revolving Credit Facility Lender Two [Member]
Short-term Debt [Line Items]
Expected extended amount for line of credit					400,000,000
Line of Credit Facility, Increase(Decrease) in Maximum Borrowing Capacity						20,000,000
Issued letters of credit	0	0
Secured revolving credit facility						270,000,000
Secured revolving credit facility borrowed	$0	$0

LongTerm_Debt_Details

Long-Term Debt (Details) (USD $)	Dec. 31, 2014		Dec. 31, 2013		Mar. 31, 2014	Aug. 01, 2013	Jul. 01, 2014
In Thousands, unless otherwise specified
Debt Instrument [Line Items]
Long-term debt	$3,226,940		$3,224,440
Long-term debt due within one year	0		-250,000
Unamortized debt discount, Net	-11,401	[1]	-5,482	[1]
Long-term debt, net	3,215,539		2,968,958
Westar Energy [Member] | Secured Debt [Member]
Debt Instrument [Line Items]
Long-term debt	2,180,000		2,250,000
Long-term pollution control bond	75,500		75,500
Westar Energy [Member] | Secured Debt [Member] | 6.00% First Mortgage Bonds Due 2014 [Member]
Debt Instrument [Line Items]
Long-term debt	0		250,000
Westar Energy [Member] | Secured Debt [Member] | 5.15% First Mortgage Bonds Due 2017 [Member]
Debt Instrument [Line Items]
Long-term debt	125,000		125,000
Westar Energy [Member] | Secured Debt [Member] | 5.95% First Mortgage Bonds Due 2035 [Member]
Debt Instrument [Line Items]
Long-term debt	125,000		125,000
Westar Energy [Member] | Secured Debt [Member] | 5.10% First Mortgage Bonds Due 2020 [Member]
Debt Instrument [Line Items]
Long-term debt	250,000		250,000
Westar Energy [Member] | Secured Debt [Member] | 5.875% First Mortgage Bonds Due 2036 [Member]
Debt Instrument [Line Items]
Long-term debt	150,000		150,000
Westar Energy [Member] | Secured Debt [Member] | 8.625% First Mortgage Bonds Due 2018 [Member]
Debt Instrument [Line Items]
Long-term debt	300,000		300,000
Westar Energy [Member] | Secured Debt [Member] | 4.125% First Mortgage Bonds Due 2042 [Member]
Debt Instrument [Line Items]
Long-term debt	550,000		550,000
Westar Energy [Member] | Secured Debt [Member] | Debt Intrument 8860 [Member]
Debt Instrument [Line Items]
Long-term debt	430,000		250,000		250,000
Westar Energy [Member] | Secured Debt [Member] | Debt Instrument 8870 [Member]
Debt Instrument [Line Items]
Long-term debt	250,000		250,000			250,000
Westar Energy [Member] | Secured Debt [Member] | Pollution Control Bonds Variable Due 2032 [Member]
Debt Instrument [Line Items]
Long-term pollution control bond	45,000		45,000
Westar Energy [Member] | Secured Debt [Member] | Pollution Control Bonds Variable Due 2032 [Member]
Debt Instrument [Line Items]
Long-term pollution control bond	30,500		30,500
KGE [Member] | Secured Debt [Member]
Debt Instrument [Line Items]
Long-term debt	875,000		625,000
Long-term pollution control bond	96,440		273,940
KGE [Member] | Secured Debt [Member] | Debt Instrument 8870 [Member]
Debt Instrument [Line Items]
Long-term debt							250,000
KGE [Member] | Secured Debt [Member] | 6.53% First Mortgage Bonds Due 2037 [Member]
Debt Instrument [Line Items]
Long-term debt	175,000		175,000
KGE [Member] | Secured Debt [Member] | 6.15% First Mortgage Bonds Due 2023 [Member]
Debt Instrument [Line Items]
Long-term debt	50,000		50,000
KGE [Member] | Secured Debt [Member] | 6.64% First Mortgage Bonds Due 2038 [Member]
Debt Instrument [Line Items]
Long-term debt	100,000		100,000
KGE [Member] | Secured Debt [Member] | 6.70% First Mortgage Bonds Due 2019 [Member]
Debt Instrument [Line Items]
Long-term debt	300,000		300,000
KGE [Member] | Secured Debt [Member] | Pollution Control Bonds Variable Due 2027 [Member]
Debt Instrument [Line Items]
Long-term pollution control bond	21,940		21,940
KGE [Member] | Secured Debt [Member] | 5.30% Pollution Control Bonds Due 2031 [Member]
Debt Instrument [Line Items]
Long-term pollution control bond	0		108,600
KGE [Member] | Secured Debt [Member] | 5.30% Pollution Control Bonds Due 2031 [Member]
Debt Instrument [Line Items]
Long-term pollution control bond	0		18,900
KGE [Member] | Secured Debt [Member] | Pollution Control Bonds Variable Due 2032 [Member]
Debt Instrument [Line Items]
Long-term pollution control bond	14,500		14,500
KGE [Member] | Secured Debt [Member] | Pollution Control Bonds Variable Due 2032 [Member]
Debt Instrument [Line Items]
Long-term pollution control bond	10,000		10,000
KGE [Member] | Secured Debt [Member] | 4.85% Pollution Control Bonds Due 2031 [Member]
Debt Instrument [Line Items]
Long-term pollution control bond	50,000		50,000
KGE [Member] | Secured Debt [Member] | 5.00% Pollution Control Bonds Due 2031 [Member]
Debt Instrument [Line Items]
Long-term pollution control bond	0		50,000
Variable Interest Entity [Member]
Debt Instrument [Line Items]
Long-term debt	194,204		221,682
Long-term debt due within one year	-27,933		-27,479
Unamortized debt discount, Net	294	[1]	599	[1]
Long-term debt, net	166,565		194,802
Variable Interest Entity [Member] | Variable Interest Entity 6.99% due 2014 [Member]
Debt Instrument [Line Items]
Long-term debt	0	[2]	316	[2]
Variable Interest Entity [Member] | Variable Interest Entity 5.92% due 2019 [Member]
Debt Instrument [Line Items]
Long-term debt	8,413	[2]	13,243	[2]
Variable Interest Entity [Member] | Variable Interest Entity 5.647% due 2021 [Member]
Debt Instrument [Line Items]
Long-term debt	$185,791	[2]	$208,123	[2]
[1]	We amortize debt discounts and premiums to interest expense over the term of the respective issues.
[2]	Portions of our payments related to this debt reduce the principal balances each year until maturity.

Longterm_Debt_Maturities_Detai

Long-term Debt Maturities (Details) (USD $)	Dec. 31, 2014
In Thousands, unless otherwise specified
Debt Instrument [Line Items]
2013	$0
2014	0
2015	125,000
2016	300,000
2017	300,000
Thereafter	2,501,940
Variable Interest Entity, Primary Beneficiary [Member]
Debt Instrument [Line Items]
2013	27,933
2014	28,309
2015	26,842
2016	28,538
2017	31,485
Thereafter	$51,097

Longterm_Debt_Narrative_Detail

Long-term Debt (Narrative) (Details) (USD $)

12 Months Ended

1 Months Ended

Dec. 31, 2014

Dec. 31, 2013

Dec. 31, 2012

Jun. 30, 2013

Jun. 30, 2014

Jan. 31, 2015

Jul. 31, 2014

Jul. 01, 2014

Jun. 01, 2013

Aug. 01, 2013

1-May-14

Mar. 31, 2014

Debt Instrument [Line Items]

Variable Rate Tax-Exempt Bonds

$121,900,000

Long-term debt

3,226,940,000

3,224,440,000

Repayments of Long-term Debt

-427,500,000

-100,000,000

-220,563,000

Interest expense on long-term debt

158,800,000

154,900,000

145,600,000

Variable Interest Entity [Member]

Debt Instrument [Line Items]

Long-term debt

194,204,000

221,682,000

Repayments of Long-term Debt

-27,479,000

-25,942,000

-28,114,000

Interest expense on long-term debt

11,400,000

13,000,000

15,100,000

KGE [Member] | First Mortgage Bond Series [Member]

Debt Instrument [Line Items]

Maximum Borrowing Capacity

3,500,000,000

Remaining Borrowing Capacity

1,300,000,000

KGE [Member] | Secured Debt [Member]

Debt Instrument [Line Items]

Long-term debt

875,000,000

625,000,000

KGE [Member] | Secured Debt [Member] | Debt Instrument 8870 [Member]

Debt Instrument [Line Items]

Long-term debt

250,000,000

KGE [Member] | Pollution Control Bond Series [Member] | DebtInstruments8780And8790 [Member]

Debt Instrument [Line Items]

Repayments of Long-term Debt

-100,000,000

KGE [Member] | Pollution Control Bond Series [Member] | Debt Instrument 8780 [Member]

Debt Instrument [Line Items]

Stated interest percentage

5.60%

KGE [Member] | Pollution Control Bond Series [Member] | Debt Instrument 8790 [Member]

Debt Instrument [Line Items]

Stated interest percentage

6.00%

KGE [Member] | Pollution Control Bond Series [Member] | Debt Instrument Seventeen [Member]

Debt Instrument [Line Items]

Repayments of Long-term Debt

-177,500,000

Westar Energy [Member] | First Mortgage Bond Series [Member]

Debt Instrument [Line Items]

Remaining Borrowing Capacity

743,200,000

Westar Energy [Member] | Secured Debt [Member]

Debt Instrument [Line Items]

Long-term debt

2,180,000,000

2,250,000,000

Westar Energy [Member] | Secured Debt [Member] | Debt Instrument Three [Member]

Debt Instrument [Line Items]

Long-term debt

125,000,000

125,000,000

Repayments of Long-term Debt

-125,000,000

Westar Energy [Member] | Secured Debt [Member] | Debt Instrument 8870 [Member]

Debt Instrument [Line Items]

Long-term debt

250,000,000

250,000,000

250,000,000

Stated interest percentage

4.63%

Westar Energy [Member] | Secured Debt [Member] | Debt Intrument One [Member]

Debt Instrument [Line Items]

Long-term debt

0

250,000,000

Repayments of Long-term Debt

-250,000,000

Westar Energy [Member] | Secured Debt [Member] | Debt Instrument 8860 [Member]

Debt Instrument [Line Items]

Long-term debt

180,000,000

Westar Energy [Member] | Secured Debt [Member] | Debt Intrument 8860 [Member]

Debt Instrument [Line Items]

Long-term debt

430,000,000

250,000,000

250,000,000

Stated interest percentage

4.10%

Westar Energy [Member] | Secured Debt [Member] | Debt Instrument Twenty-Nine [Member]

Debt Instrument [Line Items]

Long-term debt

$550,000,000

$550,000,000

Taxes_Components_of_Income_Tax

Taxes (Components of Income Tax Expense) (Details) (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Current income taxes:
Federal	$416	$135	($691)
State	-597	279	579
Deferred income taxes:
Federal	124,923	102,030	102,960
State	29,657	24,443	26,300
Investment tax credit amortization	-3,129	-3,166	-3,012
Income tax expense	$151,270	$123,721	$126,136

Taxes_Deferred_Tax_Assets_and_

Taxes (Deferred Tax Assets and Liabilities in Balance Sheet) (Details) (USD $)	Dec. 31, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Income Tax Disclosure [Abstract]
Other current liabilities (assets)	($29,636)	($37,954)
Deferred Tax Liabilities, Net	$1,445,851	$1,325,194

Taxes_Schedule_of_Deferred_Tax

Taxes (Schedule of Deferred Tax Assets and Liabilities) (Details) (USD $)	Dec. 31, 2014		Dec. 31, 2013
Income Tax Contingency [Line Items]
Deferred Tax Liabilities, Net, Noncurrent	$1,475,487,000		$1,363,148,000
Deferred Tax Liabilities, Net	1,445,851,000		1,325,194,000
Deferred Tax Assets, Net, Current	29,636,000		37,954,000
Deferred tax assets:
Business tax credit carryforward	257,827,000	[1]	212,635,000	[1]
Deferred employee benefit costs	158,102,000		85,720,000
Net operating loss carryforward	179,285,000	[2]	108,885,000	[2]
Deferred state income taxes	66,557,000		57,243,000
Deferred regulatory gain on sale-leaseback	35,706,000		38,124,000
Alternative minimum tax carryforward	24,114,000	[3]	35,666,000	[3]
Deferred compensation	29,315,000		30,022,000
Accrued liabilities	23,048,000		17,396,000
Disallowed costs	10,829,000		11,453,000
Deferred Tax Assets, Dismantling Costs	9,064,000		8,110,000
Capital loss carryforward	1,981,000		3,447,000
Other	27,689,000		20,058,000
Total gross deferred tax assets	823,517,000		628,759,000
Less: Valuation allowance	1,981,000	[4]	3,504,000	[4]
Deferred tax assets	821,536,000		625,255,000
Deferred tax liabilities:
Accelerated depreciation	1,664,367,000		1,390,669,000
Deferred employee benefit costs	153,984,000		163,742,000
Acquisition premium	163,894,000		171,907,000
Amounts due from customers for future income taxes, net	158,102,000		85,720,000
Deferred state income taxes	59,170,000		51,504,000
Pension expense tracker	15,713,000		21,165,000
Debt reacquisition costs	20,102,000		19,985,000
Storm costs	14,187,000		21,230,000
Other	17,868,000		24,527,000
Total deferred tax liabilities	2,267,387,000		1,950,449,000
Net deferred tax liabilities	1,445,851,000		1,325,194,000
Capital loss carryforwards	5,000,000
Deferred Tax Asset, Capital Loss [Member]
Deferred tax assets:
Less: Valuation allowance	2,000,000
Internal Revenue Service (IRS) [Member]
Deferred tax assets:
Business tax credit carryforward	73,500,000
Deferred tax liabilities:
Operating Loss Carryforwards	452,800,000
State and Local Jurisdiction [Member]
Deferred tax assets:
Business tax credit carryforward	$184,300,000
[1]	Based on filed tax returns and amounts expected to be reported in current year tax returns (DecemberB 31, 2014), we had available federal general business tax credits of $73.5 million and state investment tax credits of $184.3 million. The federal general business tax credits were primarily generated from production tax credits. These tax credits expire beginning in 2020 and ending in 2034. The state investment tax credits expire beginning in 2017 and ending in 2030.
[2]	As of DecemberB 31, 2014, we had a federal net operating loss carryforward of $452.8 million, which is available to offset federal taxable income. The net operating losses will expire beginning in 2031 and ending in 2034.
[3]	As of DecemberB 31, 2014, we had available an alternative minimum tax credit carryforward of $24.1 million, which has an unlimited carryforward period.
[4]	As we do not expect to realize any significant capital gains in the future, we have established a valuation allowance of $2.0 million. The total valuation allowance related to the deferred tax assets was $2.0 million as of DecemberB 31, 2014, and $3.5 million as of DecemberB 31, 2013

Taxes_Effective_Income_Tax_Rec

Taxes (Effective Income Tax Reconciliation) (Details)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Effective Income Tax Rate
Statutory federal income tax rate	35.00%	35.00%	35.00%
Corporate-owned life insurance policies	-4.00%	-5.40%	-4.90%
State income taxes	4.00%	3.80%	4.30%
Production tax credits	-2.10%	-2.30%	-2.40%
Accelerated depreciation flow through and amortization	2.00%	2.20%	1.40%
AFUDC equity	-1.30%	-1.20%	-1.00%
Amortization of federal investment tax credits	-0.70%	-0.70%	-0.70%
Capital loss utilization	-0.30%	-1.10%	-0.30%
Liability for unrecognized income tax benefits	-0.20%	0.10%	0.20%
Other	-0.50%	-1.30%	-0.70%
Effective income tax rate	31.90%	29.10%	30.90%

Taxes_Unrecognized_Tax_Benefit

Taxes (Unrecognized Tax Benefits) (Details) (USD $)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Reconciliation of Unrecognized Tax Benefits, Excluding Amounts Pertaining to Examined Tax Returns [Roll Forward]
Unrecognized income tax benefits at January 1	$1,703,000	$1,219,000	$2,483,000
Additions based on tax positions related to the current year	872,000	224,000	373,000
Additions for tax positions of prior years	813,000	325,000	0
Reductions for tax positions of prior years	-200,000	-65,000	-1,637,000
Settlements	0	0	0
Unrecognized income tax benefits at December 31	3,188,000	1,703,000	1,219,000
The amounts of unrecognized income tax benefits that, if recognized, would favorably impact our effective income tax rate	3,200,000	2,400,000	2,000,000
Accrued interest related to unrecognized income tax benefits	0	200,000
Penalties accrued	0	0
Taxes other than income taxes	$1,500,000	$1,500,000

Employee_Benefit_Plans_Funded_

Employee Benefit Plans (Funded Status) (Details) (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2014		Dec. 31, 2013		Dec. 31, 2012
Defined Benefit Plan Disclosure [Line Items]
Total Trading Securities, Assets	$35,497	[1]	$34,926
Pension Benefits [Member]
Change in Benefit Obligation:
Benefit obligation, beginning of year	823,780	[2]	928,708
Service cost	16,218		21,420		19,556
Interest cost	41,600		38,520		39,576
Plan participantsb contributions	0		0
Defined Benefit Plan, Benefits Paid	39,225		36,529
Actuarial losses (gains)	188,272		-128,339
Benefit obligation, end of year	1,030,645	[2]	823,780	[2]	928,708
Change in Plan Assets:
Fair value of plan assets, beginning of year	609,817		547,931
Actual return on plan assets	61,291		68,151
Employer contributions	26,400		27,500
Plan participantsb contributions	0		0
Benefits paid	36,367		33,765
Fair value of plan assets, end of year	661,141		609,817		547,931
Funded status, end of year	-369,504		-213,963
Amounts Recognized in the Balance Sheets Consist of:
Current liability	-2,716		-2,740
Noncurrent liability	-366,788		-211,223
Net amount recognized	-369,504		-213,963
Amounts Recognized in Regulatory Assets Consist of:
Net actuarial loss	329,572		186,365
Prior service cost	2,867		3,393
Transition obligation	0		0
Net amount recognized	332,439		189,758
Other Postretirement Benefit Plans, Defined Benefit [Member]
Change in Benefit Obligation:
Benefit obligation, beginning of year	133,061	[2]	152,564
Service cost	1,381		2,028		2,057
Interest cost	6,351		6,007		6,298
Plan participantsb contributions	4,232		2,961
Defined Benefit Plan, Benefits Paid	12,184		10,968
Actuarial losses (gains)	16,509		-19,531
Benefit obligation, end of year	141,516	[2]	133,061	[2]	152,564
Change in Plan Assets:
Fair value of plan assets, beginning of year	121,766		106,793
Actual return on plan assets	7,189		17,361
Employer contributions	0		5,318
Plan participantsb contributions	-4,074		-2,830
Benefits paid	11,680		10,536
Fair value of plan assets, end of year	121,349		121,766		106,793
Funded status, end of year	-20,167		-11,295
Amounts Recognized in the Balance Sheets Consist of:
Current liability	-246		-242
Noncurrent liability	-19,921		-11,053
Net amount recognized	-20,167		-11,295
Amounts Recognized in Regulatory Assets Consist of:
Net actuarial loss	-2,253		-18,890
Prior service cost	3,585		13,942
Transition obligation	0		0
Net amount recognized	1,332		-4,948
Supplemental Employee Retirement Plans, Defined Benefit [Member]
Change in Benefit Obligation:
Benefit obligation, end of year	29,800		27,000
Discount Rate [Member] | Pension Benefits [Member]
Change in Benefit Obligation:
Actuarial losses (gains)	123,500
Discount Rate [Member] | Other Postretirement Benefit Plans, Defined Benefit [Member]
Change in Benefit Obligation:
Actuarial losses (gains)	11,200
Mortality [Member] | Pension Benefits [Member]
Change in Benefit Obligation:
Actuarial losses (gains)	58,600
Mortality [Member] | Other Postretirement Benefit Plans, Defined Benefit [Member]
Change in Benefit Obligation:
Actuarial losses (gains)	$5,900
[1]	{F|ahBzfndlYmZpbGluZ3MtaHJkcmoLEgZYTUxEb2MiXlhCUkxEb2NHZW5JbmZvOmM4NjllMjVjOGIzYzQ1YzlhZDY3NWJiMmY0MWQ3MmQ3fFRleHRTZWxlY3Rpb246QTBGQTIzQUNGRjQwQjQ0MjlGQUNCM0UyNTU3OEY2QjgM}
[2]	(a) As of December 31, 2014 and 2013, pension benefits include non-qualified benefit obligations of $29.8 million and $27.0 million, respectively, which are funded by a trust containing assets of $35.5 million and $34.9 million, respectively, classified as trading securities. The assets in the aforementioned trust are not included in the table above. See Notes 4 and 5, "Financial Instruments and Trading Securities" and "Financial Investments," respectively, for additional information regarding these amounts.

Employee_Benefit_Plans_Plans_W

Employee Benefit Plans (Plans With a Projected Benefit Obligation and Accumulated Benefit Obligation in Excess of Plan Assets) (Details) (USD $)	Dec. 31, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Pension Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Projected benefit obligation	$1,030,645	$823,780
Fair value of plan assets	661,141	609,817
Accumulated benefit obligation	914,800	732,150
Fair value of plan assets	661,141	609,817
Discount rate	4.17%	5.07%
Compensation rate increase	4.00%	4.00%
Other Postretirement Benefit Plans, Defined Benefit [Member]
Defined Benefit Plan Disclosure [Line Items]
Accumulated benefit obligation	141,516	133,061
Fair value of plan assets	$121,349	$121,766
Discount rate	4.10%	4.88%
Compensation rate increase	0.00%	0.00%

Employee_Benefit_Plans_Net_Per

Employee Benefit Plans (Net Periodic Costs And Other Changes Recognized in Regulatory Assets) (Details) (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2014		Dec. 31, 2013		Dec. 31, 2012
Pension Benefits [Member]
Components of Net Periodic Cost (Benefit):
Service cost	$16,218		$21,420		$19,556
Interest cost	41,600		38,520		39,576
Expected return on plan assets	-36,438		-33,405		-32,283
Transition obligation, net	0		0		0
Prior service costs	526		601		612
Actuarial loss/(gain), net	19,362		33,914		32,778
Net periodic cost before regulatory adjustment	41,268		61,050		60,239
Regulatory adjustment	15,479	[1]	3,693	[1]	-6,523	[1]
Net periodic cost	56,747		64,743		53,716
Other Changes in Plan Assets and Benefit Obligations Recognized in Regulatory Assets:
Current year actuarial (gain)/loss	162,569		-163,086		18,451
Amortization of actuarial (loss)/gain	-19,362		-33,914		-32,778
Current year prior service cost	0		0		0
Amortization of prior service costs	-526		-601		-612
Amortization of transition obligation	0		0		0
Total recognized in regulatory assets	142,681		-197,601		-14,939
Total recognized in net periodic cost and regulatory assets	199,428		-132,858		38,777
Weighted-Average Actuarial Assumptions used to Determine Net Periodic Cost:
Discount rate	5.07%		4.13%		4.50%
Expected long-term return on plan assets	6.50%		6.50%		6.50%
Compensation rate increase	4.00%		4.00%		4.00%
Other Postretirement Benefit Plans, Defined Benefit [Member]
Components of Net Periodic Cost (Benefit):
Service cost	1,381		2,028		2,057
Interest cost	6,351		6,007		6,298
Expected return on plan assets	-6,576		-6,691		-5,491
Transition obligation, net	0		325		3,912
Prior service costs	2,524		2,524		2,524
Actuarial loss/(gain), net	-742		1,125		1,503
Net periodic cost before regulatory adjustment	2,938		5,318		10,803
Regulatory adjustment	4,499	[1]	2,922	[1]	23	[1]
Net periodic cost	7,437		8,240		10,826
Other Changes in Plan Assets and Benefit Obligations Recognized in Regulatory Assets:
Current year actuarial (gain)/loss	15,896		-30,201		-4,239
Amortization of actuarial (loss)/gain	742		-1,125		-1,503
Current year prior service cost	-7,834		0		0
Amortization of prior service costs	-2,524		-2,525		-2,524
Amortization of transition obligation	0		-325		-3,912
Total recognized in regulatory assets	6,280		-34,176		-12,178
Total recognized in net periodic cost and regulatory assets	$13,717		($25,936)		($1,352)
Weighted-Average Actuarial Assumptions used to Determine Net Periodic Cost:
Discount rate	4.88%		3.99%		4.25%
Expected long-term return on plan assets	6.00%		6.00%		6.00%
Compensation rate increase	4.00%		4.00%		0.00%
[1]	(a)The regulatory adjustment represents the difference between current period pension or post-retirement benefit expense and the amount of such expense recognized in setting our prices.

Employee_Benefit_Plans_Estimat

Employee Benefit Plans (Estimated Amounts From Regulatory Assets Into Net Periodic Cost) (Details) (USD $)	Dec. 31, 2014
In Thousands, unless otherwise specified
Pension Plans, Defined Benefit [Member]
Defined Benefit Plan Disclosure [Line Items]
Estimated Future Change in Regulatory Assets, Reclassification, Pension and Other Postretirement Benefit Plans, Net Gain (Loss) Recognized in Net Periodic Benefit Cost	$32,131
Estimated Future Change in Regulatory Assets, Amortization, Pension and Other Postretirement Benefit Plans, Net Prior Service Cost (Credit) Recognized in Net Periodic Benefit Cost	-520
Total	32,651
Other Postretirement Benefit Plans, Defined Benefit [Member]
Defined Benefit Plan Disclosure [Line Items]
Estimated Future Change in Regulatory Assets, Reclassification, Pension and Other Postretirement Benefit Plans, Net Gain (Loss) Recognized in Net Periodic Benefit Cost	379
Estimated Future Change in Regulatory Assets, Amortization, Pension and Other Postretirement Benefit Plans, Net Prior Service Cost (Credit) Recognized in Net Periodic Benefit Cost	-455
Total	$834

Employee_Benefit_Plans_Assumed

Employee Benefit Plans (Assumed Annual Health Care Cost Growth Rates) (Details)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Health Care Cost Trend Rate Assumed for Next Fiscal Year	1.00%	7.50%
Defined Benefit Plan, Ultimate Health Care Cost Trend Rate		5.00%
Defined Benefit Plan, Year that Rate Reaches Ultimate Trend Rate		2019

Employee_Benefit_Plans_One_Per

Employee Benefit Plans (One Percentage Change In Assumed Health Care Cost Growth Rates Effects) (Details) (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Health Care Cost Trend Rate Assumed for Next Fiscal Year	1.00%	7.50%
Defined Benefit Plan, Effect of One Percentage Point Increase on Service and Interest Cost Components	$134
Defined Benefit Plan, Effect of One Percentage Point Decrease on Service and Interest Cost Components	-120
Defined Benefit Plan, Effect of One Percentage Point Increase on Accumulated Postretirement Benefit Obligation	0
Defined Benefit Plan, Effect of One Percentage Point Decrease on Accumulated Postretirement Benefit Obligation	$0

Employee_Benefit_Plans_Fair_Va

Employee Benefit Plans (Fair Value of Plan Assets) (Details) (USD $)	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
In Thousands, unless otherwise specified
Pension Plans, Defined Benefit [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	$661,141	$609,817	$547,931
Pension Plans, Defined Benefit [Member] | Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	0	0
Pension Plans, Defined Benefit [Member] | Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	569,565	524,136
Pension Plans, Defined Benefit [Member] | Fair Value, Inputs, Level 3 [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	91,576	85,681
Pension Plans, Defined Benefit [Member] | Domestic Equity Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	184,570	183,760
Pension Plans, Defined Benefit [Member] | Domestic Equity Securities [Member] | Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	0	0
Pension Plans, Defined Benefit [Member] | Domestic Equity Securities [Member] | Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	160,574	161,272
Pension Plans, Defined Benefit [Member] | Domestic Equity Securities [Member] | Fair Value, Inputs, Level 3 [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	23,996	22,488
Pension Plans, Defined Benefit [Member] | International Equity Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	82,604	75,872
Pension Plans, Defined Benefit [Member] | International Equity Securities [Member] | Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	0	0
Pension Plans, Defined Benefit [Member] | International Equity Securities [Member] | Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	82,604	75,872
Pension Plans, Defined Benefit [Member] | International Equity Securities [Member] | Fair Value, Inputs, Level 3 [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	0	0
Pension Plans, Defined Benefit [Member] | Core Bonds [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	224,740	191,506
Pension Plans, Defined Benefit [Member] | Core Bonds [Member] | Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	0	0
Pension Plans, Defined Benefit [Member] | Core Bonds [Member] | Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	224,740	191,506
Pension Plans, Defined Benefit [Member] | Core Bonds [Member] | Fair Value, Inputs, Level 3 [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	0	0
Pension Plans, Defined Benefit [Member] | High-Yield Bonds [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	20,412	20,796
Pension Plans, Defined Benefit [Member] | High-Yield Bonds [Member] | Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	0	0
Pension Plans, Defined Benefit [Member] | High-Yield Bonds [Member] | Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	20,412	20,796
Pension Plans, Defined Benefit [Member] | High-Yield Bonds [Member] | Fair Value, Inputs, Level 3 [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	0	0
Pension Plans, Defined Benefit [Member] | Emerging Market Bonds [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	14,685	13,113
Pension Plans, Defined Benefit [Member] | Emerging Market Bonds [Member] | Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	0	0
Pension Plans, Defined Benefit [Member] | Emerging Market Bonds [Member] | Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	14,685	13,113
Pension Plans, Defined Benefit [Member] | Emerging Market Bonds [Member] | Fair Value, Inputs, Level 3 [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	0	0
Pension Plans, Defined Benefit [Member] | Combination Debt Equity Fund Member
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	61,632	58,336
Pension Plans, Defined Benefit [Member] | Combination Debt Equity Fund Member | Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	0	0
Pension Plans, Defined Benefit [Member] | Combination Debt Equity Fund Member | Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	61,632	58,336
Pension Plans, Defined Benefit [Member] | Combination Debt Equity Fund Member | Fair Value, Inputs, Level 3 [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	0	0
Pension Plans, Defined Benefit [Member] | Real Estate [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	26,439	24,022
Pension Plans, Defined Benefit [Member] | Real Estate [Member] | Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	0	0
Pension Plans, Defined Benefit [Member] | Real Estate [Member] | Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	0	0
Pension Plans, Defined Benefit [Member] | Real Estate [Member] | Fair Value, Inputs, Level 3 [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	26,439	24,022
Pension Plans, Defined Benefit [Member] | Alternative Investments [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	41,141	39,171
Pension Plans, Defined Benefit [Member] | Alternative Investments [Member] | Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	0	0
Pension Plans, Defined Benefit [Member] | Alternative Investments [Member] | Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	0	0
Pension Plans, Defined Benefit [Member] | Alternative Investments [Member] | Fair Value, Inputs, Level 3 [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	41,141	39,171
Pension Plans, Defined Benefit [Member] | Cash Equivalents [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	4,918	3,241
Pension Plans, Defined Benefit [Member] | Cash Equivalents [Member] | Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	0	0
Pension Plans, Defined Benefit [Member] | Cash Equivalents [Member] | Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	4,918	3,241
Pension Plans, Defined Benefit [Member] | Cash Equivalents [Member] | Fair Value, Inputs, Level 3 [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	0	0
Other Postretirement Benefit Plans, Defined Benefit [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	121,349	121,766	106,793
Other Postretirement Benefit Plans, Defined Benefit [Member] | Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	0	0
Other Postretirement Benefit Plans, Defined Benefit [Member] | Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	121,349	121,766
Other Postretirement Benefit Plans, Defined Benefit [Member] | Fair Value, Inputs, Level 3 [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	0	0
Other Postretirement Benefit Plans, Defined Benefit [Member] | Domestic Equity Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	63,600	64,080
Other Postretirement Benefit Plans, Defined Benefit [Member] | Domestic Equity Securities [Member] | Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	0	0
Other Postretirement Benefit Plans, Defined Benefit [Member] | Domestic Equity Securities [Member] | Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	63,600	64,080
Other Postretirement Benefit Plans, Defined Benefit [Member] | Domestic Equity Securities [Member] | Fair Value, Inputs, Level 3 [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	0	0
Other Postretirement Benefit Plans, Defined Benefit [Member] | International Equity Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	14,783	16,018
Other Postretirement Benefit Plans, Defined Benefit [Member] | International Equity Securities [Member] | Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	0	0
Other Postretirement Benefit Plans, Defined Benefit [Member] | International Equity Securities [Member] | Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	14,783	16,018
Other Postretirement Benefit Plans, Defined Benefit [Member] | International Equity Securities [Member] | Fair Value, Inputs, Level 3 [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	0	0
Other Postretirement Benefit Plans, Defined Benefit [Member] | Core Bonds [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	42,390	41,092
Other Postretirement Benefit Plans, Defined Benefit [Member] | Core Bonds [Member] | Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	0	0
Other Postretirement Benefit Plans, Defined Benefit [Member] | Core Bonds [Member] | Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	42,390	41,092
Other Postretirement Benefit Plans, Defined Benefit [Member] | Core Bonds [Member] | Fair Value, Inputs, Level 3 [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	0	0
Other Postretirement Benefit Plans, Defined Benefit [Member] | Cash Equivalents [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	576	576
Other Postretirement Benefit Plans, Defined Benefit [Member] | Cash Equivalents [Member] | Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	0	0
Other Postretirement Benefit Plans, Defined Benefit [Member] | Cash Equivalents [Member] | Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	576	576
Other Postretirement Benefit Plans, Defined Benefit [Member] | Cash Equivalents [Member] | Fair Value, Inputs, Level 3 [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	$0	$0

Employee_Benefit_Plans_Changes

Employee Benefit Plans (Changes in Level 3 Plan Assets Measured at Fair Value on a Recurring Basis) (Details) (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Defined Benefit Plan Disclosure [Line Items]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset Value	$32,565	$30,003	$12,764
Fair Value, Inputs, Level 3 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset Value	91,576	85,681	84,955
Defined Benefit Plan, Actual Return on Plan Assets Still Held	4,446	9,088
Defined Benefit Plan, Actual Return on Plan Assets Sold During Period	1,394	826
Purchases, issuances and settlements, net	55	-9,188
Domestic Equity Securities [Member] | Fair Value, Inputs, Level 3 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset Value	23,996	22,488	18,493
Defined Benefit Plan, Actual Return on Plan Assets Still Held	-154	3,845
Defined Benefit Plan, Actual Return on Plan Assets Sold During Period	1,365	0
Purchases, issuances and settlements, net	297	150
Real Estate [Member] | Fair Value, Inputs, Level 3 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset Value	26,439	24,022	20,927
Defined Benefit Plan, Actual Return on Plan Assets Still Held	2,630	3,307
Defined Benefit Plan, Actual Return on Plan Assets Sold During Period	-29	0
Purchases, issuances and settlements, net	-242	-212
Alternative Investments [Member] | Fair Value, Inputs, Level 3 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset Value	41,141	39,171	45,535
Defined Benefit Plan, Actual Return on Plan Assets Still Held	1,970	1,936
Defined Benefit Plan, Actual Return on Plan Assets Sold During Period	0	826
Purchases, issuances and settlements, net	$0	($9,126)

Employee_Benefit_Plans_Expecte

Employee Benefit Plans (Expected Cash Flows Related To Pension and Post-Retirement Benefit Plans) (Details) (USD $)	12 Months Ended
In Millions, unless otherwise specified	Dec. 31, 2014
Plan Trust [Member] | Pension Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
2014	$42
2014	-35.1
2015	-37.3
2016	-39.5
2017	-41.9
2018	-44.2
2019 - 2022	-257.8
Plan Trust [Member] | Other Postretirement Benefit Plans, Defined Benefit [Member]
Defined Benefit Plan Disclosure [Line Items]
2014	0
2014	-8.2
2015	-8.3
2016	-8.4
2017	-8.6
2018	-8.7
2019 - 2022	-43.5
Company Assets [Member] | Pension Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
2014	-2.8
2015	-2.8
2016	-2.8
2017	-2.7
2018	-2.7
2019 - 2022	-13
Company Assets [Member] | Other Postretirement Benefit Plans, Defined Benefit [Member]
Defined Benefit Plan Disclosure [Line Items]
2014	-0.2
2015	-0.2
2016	-0.2
2017	-0.2
2018	-0.2
2019 - 2022	($1)

Employee_Benefit_Plans_Compens

Employee Benefit Plans (Compensation expense and income tax benefits related to stock-based compensation arrangements included in net income) (Details) (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Defined Benefit Plan Disclosure [Line Items]
Allocated Share-based Compensation Expense	$7,193	$8,121	$7,203
Employee Service Share-based Compensation, Tax Benefit from Compensation Expense	$2,845	$3,212	$2,849

Employee_Benefit_Plans_RSU_act

Employee Benefit Plans (RSU activity for awards) (Details) (USD $)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
RSU Awards With Only Service Requirements [Member]
Defined Benefit Plan Disclosure [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Vested in Period, Total Fair Value	$3,900,000	$3,700,000	$3,700,000
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested [Roll Forward]
Nonvested balance, beginning of year	352,500	351,100	368,500
Granted	131,500	139,600	131,000
Vested	-118,200	-125,500	-127,800
Forfeited	-23,600	-12,700	-20,600
Nonvested balance, end of year	342,200	352,500	351,100
Weighted Average Grant Date Fair Value, beginning of year	$28.38	$25.47	$23.83
Grants in Period, Weighted Average Grant Date Fair Value	$34.53	$31.06	$27.82
Vested in Period, Weighted Average Grant Date Fair Value	$26.19	$23.22	$23.34
Forfeited in Period, Weighted Average Grant Date Fair Value	$30	$28.35	$24.40
Weighted Average Grant Date Fair Value, end of year	$31.38	$28.38	$25.47
RSU Awards With Performance Measures [Member]
Defined Benefit Plan Disclosure [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Vested in Period, Total Fair Value	$500,000	$2,300,000	$3,600,000
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested [Roll Forward]
Nonvested balance, beginning of year	350,100	340,100	324,200
Granted	126,100	134,400	122,300
Vested	-108,200	-112,500	-88,200
Forfeited	-22,900	-11,900	-18,200
Nonvested balance, end of year	345,100	350,100	340,100
Weighted Average Grant Date Fair Value, beginning of year	$30.35	$29.20	$28.31
Grants in Period, Weighted Average Grant Date Fair Value	$35.97	$31.54	$28.84
Vested in Period, Weighted Average Grant Date Fair Value	$30.56	$28.29	$25.46
Forfeited in Period, Weighted Average Grant Date Fair Value	$30.70	$30.45	$29
Weighted Average Grant Date Fair Value, end of year	$32.31	$30.35	$29.20

Employee_Benefit_Plans_Textual

Employee Benefit Plans (Textual) (Details) (USD $)	12 Months Ended
	Dec. 31, 2014		Dec. 31, 2013		Dec. 31, 2012	19-May-11
Defined Benefit Plan Disclosure [Line Items]
Total Trading Securities, Assets	$35,497,000	[1]	$34,926,000
Defined Benefit Plan Target Allocation Percentage Of Assets Of Any One Industry	25.00%
401k Savings Plan Matching Contributions	7,000,000		6,900,000		7,100,000
Percentage of RSU Award, Minimum	0.00%
Percentage of RSU Award, Maximum	200.00%
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Expected Volatility Rate, Minimum	15.20%		15.00%
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Expected Volatility Rate, Maximum	23.30%		23.50%
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Risk Free Interest Rate, Minimum	0.30%		0.30%
Common stock, shares issued	131,687,454		128,254,229
Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Total Trading Securities, Assets	35,329,000	[1]	34,760,000
US Government Securities, at Carrying Value	59,000,000
Pension Plans, Defined Benefit [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Benefits Paid	39,225,000		36,529,000
Benefit obligation for certain retirement benefits	1,030,645,000	[2]	823,780,000	[2]	928,708,000
Other Postretirement Benefit Plans, Defined Benefit [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Benefits Paid	12,184,000		10,968,000
Benefit obligation for certain retirement benefits	141,516,000	[2]	133,061,000	[2]	152,564,000
Supplemental Employee Retirement Plans, Defined Benefit [Member]
Defined Benefit Plan Disclosure [Line Items]
Benefit obligation for certain retirement benefits	29,800,000		27,000,000
KGE [Member]
Defined Benefit Plan Disclosure [Line Items]
Subsidiary Interest in Defined Benefit Plans	47.00%
Debt Securities [Member] | Pension Plans, Defined Benefit [Member]
Defined Benefit Plan Disclosure [Line Items]
Target Defined Benefit Plan Asset Allocations	39.00%
Debt Securities [Member] | Other Postretirement Benefit Plans, Defined Benefit [Member]
Defined Benefit Plan Disclosure [Line Items]
Target Defined Benefit Plan Asset Allocations	35.00%
Equity Securities [Member] | Pension Plans, Defined Benefit [Member]
Defined Benefit Plan Disclosure [Line Items]
Target Defined Benefit Plan Asset Allocations	39.00%
Equity Securities [Member] | Other Postretirement Benefit Plans, Defined Benefit [Member]
Defined Benefit Plan Disclosure [Line Items]
Target Defined Benefit Plan Asset Allocations	65.00%
Alternative Investments [Member] | Pension Plans, Defined Benefit [Member]
Defined Benefit Plan Disclosure [Line Items]
Target Defined Benefit Plan Asset Allocations	12.00%
Other Investments [Member] | Pension Plans, Defined Benefit [Member]
Defined Benefit Plan Disclosure [Line Items]
Target Defined Benefit Plan Asset Allocations	10.00%
Long Term Incentive and Share Award [Member]
Defined Benefit Plan Disclosure [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Authorized						8,250,000
Share-based Compensation Arrangement by Share-based Payment Award, Shares Awarded	5,000,000
Long Term Incentive and Share Award Plan Executive Stock For Compensation Program [Member]
Defined Benefit Plan Disclosure [Line Items]
Common Stock Dividends, Shares	403		551		666
Common stock, shares issued	1,944		3,456		1,461
RSU Awards With Performance Measures [Member]
Defined Benefit Plan Disclosure [Line Items]
Employee Service Share-based Compensation, Nonvested Awards, Total Compensation Cost Not yet Recognized	3,800,000		4,000,000
Employee Service Share-based Compensation, Nonvested Awards, Total Compensation Cost Not yet Recognized, Period for Recognition	1 year 8 months
Share-based Compensation Award Fair Value, Vested During Period	500,000		2,300,000		3,600,000
RSU Awards With Only Service Requirements [Member]
Defined Benefit Plan Disclosure [Line Items]
Employee Service Share-based Compensation, Nonvested Awards, Total Compensation Cost Not yet Recognized	4,400,000		4,400,000
Employee Service Share-based Compensation, Nonvested Awards, Total Compensation Cost Not yet Recognized, Period for Recognition	1 year 11 months
Share-based Compensation Award Fair Value, Vested During Period	$3,900,000		$3,700,000		$3,700,000
[1]	{F|ahBzfndlYmZpbGluZ3MtaHJkcmoLEgZYTUxEb2MiXlhCUkxEb2NHZW5JbmZvOmM4NjllMjVjOGIzYzQ1YzlhZDY3NWJiMmY0MWQ3MmQ3fFRleHRTZWxlY3Rpb246QTBGQTIzQUNGRjQwQjQ0MjlGQUNCM0UyNTU3OEY2QjgM}
[2]	(a) As of December 31, 2014 and 2013, pension benefits include non-qualified benefit obligations of $29.8 million and $27.0 million, respectively, which are funded by a trust containing assets of $35.5 million and $34.9 million, respectively, classified as trading securities. The assets in the aforementioned trust are not included in the table above. See Notes 4 and 5, "Financial Instruments and Trading Securities" and "Financial Investments," respectively, for additional information regarding these amounts.

Wolf_Creek_Employee_Benefit_Pl2

Wolf Creek Employee Benefit Plans (Funded Status) (Details) (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2014		Dec. 31, 2013		Dec. 31, 2012
Wolf Creek [Member]
Change in Plan Assets:
Fair value of plan assets, end of year	$124,660		$114,734
Pension Benefits [Member]
Change in Benefit Obligation:
Benefit obligation, beginning of year	823,780	[1]	928,708
Service cost	16,218		21,420		19,556
Interest cost	41,600		38,520		39,576
Plan participantsb contributions	0		0
Defined Benefit Plan, Benefits Paid	-39,225		-36,529
Actuarial losses (gains)	188,272		-128,339
Amendments	0		0
Benefit obligation, end of year	1,030,645	[1]	823,780	[1]	928,708
Change in Plan Assets:
Fair value of plan assets, beginning of year	609,817		547,931
Actual return on plan assets	61,291		68,151
Employer contributions	26,400		27,500
Plan participants' contribution	0		0
Benefits paid	36,367		33,765
Fair value of plan assets, end of year	661,141		609,817		547,931
Funded status, end of year	-369,504		-213,963
Amounts Recognized in the Balance Sheet Consist of:
Current liability	-2,716		-2,740
Noncurrent liability	-366,788		-211,223
Net amount recognized	-369,504		-213,963
Amounts Recognized in Regulatory Assets Consist of:
Net actuarial loss	329,572		186,365
Prior service cost	2,867		3,393
Transition obligation	0		0
Net amount recognized	332,439		189,758
Pension Benefits [Member] | Wolf Creek [Member]
Change in Benefit Obligation:
Benefit obligation, beginning of year	162,820		176,891
Service cost	5,695		6,835		6,062
Interest cost	8,469		7,562		7,537
Plan participantsb contributions	0		0
Defined Benefit Plan, Benefits Paid	-5,039		-4,349
Actuarial losses (gains)	38,375		-24,119
Benefit obligation, end of year	210,320		162,820		176,891
Change in Plan Assets:
Fair value of plan assets, beginning of year	114,734		98,051
Actual return on plan assets	7,626		13,166
Employer contributions	7,089		7,624
Plan participants' contribution	0		0
Benefits paid	-4,789		-4,107
Fair value of plan assets, end of year	124,660		114,734		98,051
Funded status, end of year	-85,660		-48,086
Amounts Recognized in the Balance Sheet Consist of:
Current liability	-247		-237
Noncurrent liability	-85,413		-47,849
Net amount recognized	-85,660		-48,086
Amounts Recognized in Regulatory Assets Consist of:
Net actuarial loss	65,049		29,203
Prior service cost	559		617
Net amount recognized	65,608		29,820
Other Postretirement Benefit Plans, Defined Benefit [Member]
Change in Benefit Obligation:
Benefit obligation, beginning of year	133,061	[1]	152,564
Service cost	1,381		2,028		2,057
Interest cost	6,351		6,007		6,298
Plan participantsb contributions	4,232		2,961
Defined Benefit Plan, Benefits Paid	-12,184		-10,968
Actuarial losses (gains)	16,509		-19,531
Amendments	-7,834		0
Benefit obligation, end of year	141,516	[1]	133,061	[1]	152,564
Change in Plan Assets:
Fair value of plan assets, beginning of year	121,766		106,793
Actual return on plan assets	7,189		17,361
Employer contributions	0		5,318
Plan participants' contribution	4,074		2,830
Benefits paid	11,680		10,536
Fair value of plan assets, end of year	121,349		121,766		106,793
Funded status, end of year	-20,167		-11,295
Amounts Recognized in the Balance Sheet Consist of:
Current liability	-246		-242
Noncurrent liability	-19,921		-11,053
Net amount recognized	-20,167		-11,295
Amounts Recognized in Regulatory Assets Consist of:
Net actuarial loss	-2,253		-18,890
Prior service cost	3,585		13,942
Transition obligation	0		0
Net amount recognized	1,332		-4,948
Other Postretirement Benefit Plans, Defined Benefit [Member] | Wolf Creek [Member]
Change in Benefit Obligation:
Benefit obligation, beginning of year	10,010		11,020
Service cost	173		206		191
Interest cost	464		413		411
Plan participantsb contributions	766		696
Defined Benefit Plan, Benefits Paid	-1,292		-1,022
Actuarial losses (gains)	-1,881		-1,303
Benefit obligation, end of year	8,240		10,010		11,020
Change in Plan Assets:
Fair value of plan assets, beginning of year	17		13
Actual return on plan assets	0		0
Employer contributions	515		330
Plan participants' contribution	766		696
Benefits paid	-1,292		-1,022
Fair value of plan assets, end of year	6		17		13
Funded status, end of year	-8,234		-9,993
Amounts Recognized in the Balance Sheet Consist of:
Current liability	-575		-614
Noncurrent liability	-7,659		-9,379
Net amount recognized	-8,234		-9,993
Amounts Recognized in Regulatory Assets Consist of:
Net actuarial loss	29		2,076
Prior service cost	0		0
Net amount recognized	29		2,076
Discount Rate [Member] | Pension Benefits [Member]
Change in Benefit Obligation:
Actuarial losses (gains)	123,500
Discount Rate [Member] | Pension Benefits [Member] | Wolf Creek [Member]
Change in Benefit Obligation:
Actuarial losses (gains)	26,900
Discount Rate [Member] | Other Postretirement Benefit Plans, Defined Benefit [Member]
Change in Benefit Obligation:
Actuarial losses (gains)	11,200
Discount Rate [Member] | Other Postretirement Benefit Plans, Defined Benefit [Member] | Wolf Creek [Member]
Change in Benefit Obligation:
Actuarial losses (gains)	600
Mortality [Member] | Pension Benefits [Member]
Change in Benefit Obligation:
Actuarial losses (gains)	58,600
Mortality [Member] | Pension Benefits [Member] | Wolf Creek [Member]
Change in Benefit Obligation:
Actuarial losses (gains)	11,300
Mortality [Member] | Other Postretirement Benefit Plans, Defined Benefit [Member]
Change in Benefit Obligation:
Actuarial losses (gains)	5,900
Mortality [Member] | Other Postretirement Benefit Plans, Defined Benefit [Member] | Wolf Creek [Member]
Change in Benefit Obligation:
Actuarial losses (gains)	$200
[1]	(a) As of December 31, 2014 and 2013, pension benefits include non-qualified benefit obligations of $29.8 million and $27.0 million, respectively, which are funded by a trust containing assets of $35.5 million and $34.9 million, respectively, classified as trading securities. The assets in the aforementioned trust are not included in the table above. See Notes 4 and 5, "Financial Instruments and Trading Securities" and "Financial Investments," respectively, for additional information regarding these amounts.

Wolf_Creek_Employee_Benefit_Pl3

Wolf Creek Employee Benefit Plans Wolf Creek Employee Benefit Plans (Plans With a Projected Benefit Obligation and Accumulated Benefit Obligation in Excess of Plan Assets) (Details) (Details) (USD $)	Dec. 31, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Pension Plans, Defined Benefit [Member]
Defined Benefit Plan Disclosure [Line Items]
Projected benefit obligation	$1,030,645	$823,780
Fair value of plan assets	661,141	609,817
Accumulated benefit obligation	914,800	732,150
Fair value of plan assets	661,141	609,817
Discount rate	4.17%	5.07%
Compensation rate increase	4.00%	4.00%
Other Postretirement Benefit Plans, Defined Benefit [Member]
Defined Benefit Plan Disclosure [Line Items]
Accumulated benefit obligation	141,516	133,061
Fair value of plan assets	121,349	121,766
Discount rate	4.10%	4.88%
Compensation rate increase	0.00%	0.00%
Wolf Creek [Member] | Pension Plans, Defined Benefit [Member]
Defined Benefit Plan Disclosure [Line Items]
Projected benefit obligation	210,320	162,820
Fair value of plan assets	124,660	114,734
Accumulated benefit obligation	179,228	137,459
Fair value of plan assets	124,660	114,734
Discount rate	4.20%	5.11%
Compensation rate increase	4.00%	4.00%
Wolf Creek [Member] | Other Postretirement Benefit Plans, Defined Benefit [Member]
Defined Benefit Plan Disclosure [Line Items]
Accumulated benefit obligation	8,240	10,010
Fair value of plan assets	$6	$16
Discount rate	3.89%	4.70%
Compensation rate increase	0.00%	0.00%

Wolf_Creek_Employee_Benefit_Pl4

Wolf Creek Employee Benefit Plans Wolf Creek Employee Benefit Plans (Net Periodic Costs And Other Changes Recognized in Regulatory Assets) (Details) (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2014		Dec. 31, 2013		Dec. 31, 2012
Pension Benefits [Member]
Components of Net Periodic Cost (Benefit):
Service cost	$16,218		$21,420		$19,556
Interest cost	41,600		38,520		39,576
Expected return on plan assets	-36,438		-33,405		-32,283
Transition obligation, net	0		0		0
Prior service costs	526		601		612
Actuarial loss, net	19,362		33,914		32,778
Net periodic cost before regulatory adjustment	41,268		61,050		60,239
Regulatory adjustment	15,479	[1]	3,693	[1]	-6,523	[1]
Net periodic cost	56,747		64,743		53,716
Other Changes in Plan Assets and Benefit Obligations Recognized in Regulatory Assets:
Current year actuarial (gain)/loss	162,569		-163,086		18,451
Amortization of actuarial loss	-19,362		-33,914		-32,778
Current year prior service cost	0		0		0
Amortization of prior service costs	-526		-601		-612
Amortization of transition obligation	0		0		0
Total recognized in regulatory assets	142,681		-197,601		-14,939
Total recognized in net periodic cost and regulatory assets	199,428		-132,858		38,777
Weighted-Average Actuarial Assumptions used to Determine Net Periodic Cost:
Discount rate	5.07%		4.13%		4.50%
Expected long-term return on plan assets	6.50%		6.50%		6.50%
Compensation rate increase	4.00%		4.00%		4.00%
Pension Benefits [Member] | Wolf Creek [Member]
Components of Net Periodic Cost (Benefit):
Service cost	5,695		6,835		6,062
Interest cost	8,469		7,562		7,537
Expected return on plan assets	-8,084		-7,373		-6,577
Transition obligation, net	0		0		0
Prior service costs	58		58		6
Actuarial loss, net	2,987		5,421		5,366
Net periodic cost before regulatory adjustment	9,125		12,503		12,394
Regulatory adjustment	2,328	[2]	-641	[2]	-1,776	[2]
Net periodic cost	11,453		11,862		10,618
Other Changes in Plan Assets and Benefit Obligations Recognized in Regulatory Assets:
Current year actuarial (gain)/loss	38,833		-29,911		4,629
Amortization of actuarial loss	-2,987		-5,421		-5,366
Current year prior service cost	0		0		650
Amortization of prior service costs	-58		-58		-6
Amortization of transition obligation	0		0		0
Total recognized in regulatory assets	35,788		-35,390		-93
Total recognized in net periodic cost and regulatory assets	47,241		-23,528		10,525
Weighted-Average Actuarial Assumptions used to Determine Net Periodic Cost:
Discount rate	5.11%		4.16%		4.55%
Expected long-term return on plan assets	7.50%		7.50%		7.50%
Compensation rate increase	4.00%		4.00%		4.00%
Other Postretirement Benefit Plans, Defined Benefit [Member]
Components of Net Periodic Cost (Benefit):
Service cost	1,381		2,028		2,057
Interest cost	6,351		6,007		6,298
Expected return on plan assets	-6,576		-6,691		-5,491
Transition obligation, net	0		325		3,912
Prior service costs	2,524		2,524		2,524
Actuarial loss, net	-742		1,125		1,503
Net periodic cost before regulatory adjustment	2,938		5,318		10,803
Regulatory adjustment	4,499	[1]	2,922	[1]	23	[1]
Net periodic cost	7,437		8,240		10,826
Other Changes in Plan Assets and Benefit Obligations Recognized in Regulatory Assets:
Current year actuarial (gain)/loss	15,896		-30,201		-4,239
Amortization of actuarial loss	742		-1,125		-1,503
Current year prior service cost	-7,834		0		0
Amortization of prior service costs	-2,524		-2,525		-2,524
Amortization of transition obligation	0		-325		-3,912
Total recognized in regulatory assets	6,280		-34,176		-12,178
Total recognized in net periodic cost and regulatory assets	13,717		-25,936		-1,352
Weighted-Average Actuarial Assumptions used to Determine Net Periodic Cost:
Discount rate	4.88%		3.99%		4.25%
Expected long-term return on plan assets	6.00%		6.00%		6.00%
Compensation rate increase	4.00%		4.00%		0.00%
Other Postretirement Benefit Plans, Defined Benefit [Member] | Wolf Creek [Member]
Components of Net Periodic Cost (Benefit):
Service cost	173		206		191
Interest cost	464		413		411
Expected return on plan assets	0		0		0
Transition obligation, net	0		0		57
Prior service costs	0		0		0
Actuarial loss, net	165		265		234
Net periodic cost before regulatory adjustment	802		884		893
Regulatory adjustment	0	[2]	0	[2]	0	[2]
Net periodic cost	802		884		893
Other Changes in Plan Assets and Benefit Obligations Recognized in Regulatory Assets:
Current year actuarial (gain)/loss	-1,881		-1,303		669
Amortization of actuarial loss	-165		-265		-234
Current year prior service cost	0		0		0
Amortization of prior service costs	0		0		0
Amortization of transition obligation	0		0		-57
Total recognized in regulatory assets	-2,046		-1,568		378
Total recognized in net periodic cost and regulatory assets	($1,244)		($684)		$1,271
Weighted-Average Actuarial Assumptions used to Determine Net Periodic Cost:
Discount rate	4.70%		3.78%		4.10%
Expected long-term return on plan assets	0.00%		0.00%		0.00%
Compensation rate increase	0.00%		0.00%		0.00%
[1]	(a)The regulatory adjustment represents the difference between current period pension or post-retirement benefit expense and the amount of such expense recognized in setting our prices.
[2]	The regulatory adjustment represents the difference between current period pension or post-retirement benefit expense and the amount of such expense recognized in setting our prices.

Wolf_Creek_Employee_Benefit_Pl5

Wolf Creek Employee Benefit Plans Wolf Creek Employee Benefit Plans (Estimated Amounts From Regulatory Assets Into Net Periodic Cost) (Details) (USD $)	Dec. 31, 2014
In Thousands, unless otherwise specified
Pension Benefits [Member]
Actuarial loss	($32,131)
Prior service cost	-520
Total	32,651
Pension Benefits [Member] | Wolf Creek [Member]
Actuarial loss	-5,930
Prior service cost	-57
Total	5,987
Other Postretirement Benefit Plans, Defined Benefit [Member]
Actuarial loss	-379
Prior service cost	-455
Total	834
Other Postretirement Benefit Plans, Defined Benefit [Member] | Wolf Creek [Member]
Actuarial loss	-2
Prior service cost	0
Total	$2

Wolf_Creek_Employee_Benefit_Pl6

Wolf Creek Employee Benefit Plans Wolf Creek Employee Benefit Plans (Assumed Annual Health Care Cost Growth Rates) (Details)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013
Health care cost trend rate assumed for next year	1.00%	7.50%
Rate to which the cost trend rate is assumed to decline (the ultimate trend rate)		5.00%
Year that the rate reaches the ultimate trend rate		2019
Wolf Creek [Member]
Health care cost trend rate assumed for next year	7.00%	7.50%
Rate to which the cost trend rate is assumed to decline (the ultimate trend rate)	5.00%	5.00%
Year that the rate reaches the ultimate trend rate	2019	2019

Wolf_Creek_Employee_Benefit_Pl7

Wolf Creek Employee Benefit Plans Wolf Creek Employee Benefit Plans (One Percentage Change In Assumed Health Care Cost Growth Rates Effects) (Details) (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013
Defined Benefit Plan, Health Care Cost Trend Rate Assumed for Next Fiscal Year	1.00%	7.50%
Effect on total of service and interest cost from one-percentage-point increase	$134
Effect on total of service and interest cost from one-percentage-point decrease	-120
Effect on post-retirement benefit obligation from one-percentage-point increase	0
Effect on post-retirement benefit obligation from one-percentage-point decrease	0
Wolf Creek [Member]
Defined Benefit Plan, Health Care Cost Trend Rate Assumed for Next Fiscal Year	7.00%	7.50%
Effect on total of service and interest cost from one-percentage-point increase	-8
Effect on total of service and interest cost from one-percentage-point decrease	8
Effect on post-retirement benefit obligation from one-percentage-point increase	-111
Effect on post-retirement benefit obligation from one-percentage-point decrease	$113

Wolf_Creek_Employee_Benefit_Pl8

Wolf Creek Employee Benefit Plans Wolf Creek Employee Benefit Plans (Fair Value of Plan Assets) (Details) (Wolf Creek [Member], USD $)	Dec. 31, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Fair value of pension plan assets	$124,660	$114,734
Level 1
Fair value of pension plan assets	0	0
Level 2
Fair value of pension plan assets	114,702	105,493
Level 3
Fair value of pension plan assets	9,958	9,241
Domestic Equity Securities [Member]
Fair value of pension plan assets	31,580	30,599
Domestic Equity Securities [Member] | Level 1
Fair value of pension plan assets	0	0
Domestic Equity Securities [Member] | Level 2
Fair value of pension plan assets	31,580	30,599
Domestic Equity Securities [Member] | Level 3
Fair value of pension plan assets	0	0
International Equity Securities [Member]
Fair value of pension plan assets	38,624	36,868
International Equity Securities [Member] | Level 1
Fair value of pension plan assets	0	0
International Equity Securities [Member] | Level 2
Fair value of pension plan assets	38,624	36,868
International Equity Securities [Member] | Level 3
Fair value of pension plan assets	0	0
Core Bonds [Member]
Fair value of pension plan assets	31,854	26,926
Core Bonds [Member] | Level 1
Fair value of pension plan assets	0	0
Core Bonds [Member] | Level 2
Fair value of pension plan assets	31,854	26,926
Core Bonds [Member] | Level 3
Fair value of pension plan assets	0	0
Real Estate [Member]
Fair value of pension plan assets	11,962	10,534
Real Estate [Member] | Level 1
Fair value of pension plan assets	0	0
Real Estate [Member] | Level 2
Fair value of pension plan assets	6,313	5,440
Real Estate [Member] | Level 3
Fair value of pension plan assets	5,649	5,094
Commodities [Member]
Fair value of pension plan assets	5,887	5,245
Commodities [Member] | Level 1
Fair value of pension plan assets	0	0
Commodities [Member] | Level 2
Fair value of pension plan assets	5,887	5,245
Commodities [Member] | Level 3
Fair value of pension plan assets	0	0
Alternative Investments [Member]
Fair value of pension plan assets	4,309	4,147
Alternative Investments [Member] | Level 1
Fair value of pension plan assets	0	0
Alternative Investments [Member] | Level 2
Fair value of pension plan assets	0	0
Alternative Investments [Member] | Level 3
Fair value of pension plan assets	4,309	4,147
Cash Equivalents [Member]
Fair value of pension plan assets	444	415
Cash Equivalents [Member] | Level 1
Fair value of pension plan assets	0	0
Cash Equivalents [Member] | Level 2
Fair value of pension plan assets	444	415
Cash Equivalents [Member] | Level 3
Fair value of pension plan assets	$0	$0

Wolf_Creek_Employee_Benefit_Pl9

Wolf Creek Employee Benefit Plans Wolf Creek Employee Benefit Plans (Changes in Level 3 Plan Assets Measured at Fair Value on a Recurring Basis) (Details) (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance at period start			$12,764
Balance at period end	32,565	30,003	12,764
Level 3
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance at period start	85,681	84,955
Actual gain (loss) on plan assets relating to assets still held at the reporting date	-4,446	-9,088
Actual gain (loss) on plan assets relating to assets sold during the period	1,394	826
Purchases, issuances and settlements, net	55	-9,188
Balance at period end	91,576	85,681
Level 3 | Wolf Creek [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance at period start	9,241	8,441
Actual gain (loss) on plan assets relating to assets still held at the reporting date	-717	-800
Balance at period end	9,958	9,241
Real Estate [Member] | Level 3
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance at period start	24,022	20,927
Actual gain (loss) on plan assets relating to assets still held at the reporting date	-2,630	-3,307
Actual gain (loss) on plan assets relating to assets sold during the period	-29	0
Purchases, issuances and settlements, net	-242	-212
Balance at period end	26,439	24,022
Real Estate [Member] | Level 3 | Wolf Creek [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance at period start	5,094	4,541
Actual gain (loss) on plan assets relating to assets still held at the reporting date	-555	-553
Balance at period end	5,649	5,094
Alternative Investments [Member] | Level 3
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance at period start	39,171	45,535
Actual gain (loss) on plan assets relating to assets still held at the reporting date	-1,970	-1,936
Actual gain (loss) on plan assets relating to assets sold during the period	0	826
Purchases, issuances and settlements, net	0	-9,126
Balance at period end	41,141	39,171
Alternative Investments [Member] | Level 3 | Wolf Creek [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance at period start	4,147	3,900
Actual gain (loss) on plan assets relating to assets still held at the reporting date	-162	-247
Balance at period end	$4,309	$4,147

Recovered_Sheet1

Wolf Creek Employee Benefit Plans Wolf Creek Employee Benefit Plans (Expected Cash Flows Related To Pension and Post-Retirement Benefit Plans) (Details) (USD $)	12 Months Ended
In Millions, unless otherwise specified	Dec. 31, 2014
Plan Trust [Member] | Pension Benefits [Member]
Expected contributions:
2014	$42
Expected benefit payments:
2014	-35.1
2015	-37.3
2016	-39.5
2017	-41.9
2018	-44.2
2019 - 2022	-257.8
Plan Trust [Member] | Pension Benefits [Member] | Wolf Creek [Member]
Expected contributions:
2014	4.7
Expected benefit payments:
2014	-5.4
2015	-6.1
2016	-6.8
2017	-7.5
2018	-8.2
2019 - 2022	-51
Plan Trust [Member] | Other Postretirement Benefit Plans, Defined Benefit [Member]
Expected contributions:
2014	0
Expected benefit payments:
2014	-8.2
2015	-8.3
2016	-8.4
2017	-8.6
2018	-8.7
2019 - 2022	-43.5
Plan Trust [Member] | Other Postretirement Benefit Plans, Defined Benefit [Member] | Wolf Creek [Member]
Expected contributions:
2014	0.6
Expected benefit payments:
2014	-0.6
2015	-0.6
2016	-0.6
2017	-0.6
2018	-0.7
2019 - 2022	-3.2
Company Assets [Member] | Pension Benefits [Member]
Expected benefit payments:
2014	-2.8
2015	-2.8
2016	-2.8
2017	-2.7
2018	-2.7
2019 - 2022	-13
Company Assets [Member] | Pension Benefits [Member] | Wolf Creek [Member]
Expected benefit payments:
2014	-0.2
2015	-0.2
2016	-0.2
2017	-0.2
2018	-0.2
2019 - 2022	-1.1
Company Assets [Member] | Other Postretirement Benefit Plans, Defined Benefit [Member]
Expected benefit payments:
2014	-0.2
2015	-0.2
2016	-0.2
2017	-0.2
2018	-0.2
2019 - 2022	-1
Company Assets [Member] | Other Postretirement Benefit Plans, Defined Benefit [Member] | Wolf Creek [Member]
Expected benefit payments:
2014	0
2015	0
2016	0
2017	0
2018	0
2019 - 2022	$0

Recovered_Sheet2

Wolf Creek Employee Benefit Plans (Textual) (Details) (USD $)	12 Months Ended
In Millions, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
401k Savings Plan Matching Contributions	$7	$6.90	$7.10
KGE [Member]
Subsidiary's interest, percentage	47.00%
Wolf Creek [Member]
401k Savings Plan Matching Contributions	$1.40	$1.40	$1.30
International Equity Securities [Member] | Wolf Creek [Member]
Target Defined Benefit Plan Asset Allocations	31.00%
Domestic Equity Securities [Member] | Wolf Creek [Member]
Target Defined Benefit Plan Asset Allocations	25.00%
Debt Securities [Member] | Wolf Creek [Member]
Target Defined Benefit Plan Asset Allocations	25.00%
Real Estate [Member] | Wolf Creek [Member]
Target Defined Benefit Plan Asset Allocations	10.00%
Commodity [Member] | Wolf Creek [Member]
Target Defined Benefit Plan Asset Allocations	5.00%
Other Investments [Member] | Wolf Creek [Member]
Target Defined Benefit Plan Asset Allocations	4.00%

Commitments_And_Contingencies_1

Commitments And Contingencies (Details) (USD $)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
	phases
	MW
	Y
Aggregate Amount of Required Payments [Abstract]
2014	$406,859,000
2015	39,551,000
2016	9,223,000
Thereafter	27,247,000
Total amount committed	482,880,000
Environmental Projects [Abstract]
Entity Share of Environmental Upgrades of Jointly Owned Plant	610,000,000
Proposed Increase In Annual Retail Revenues	4,000,000	30,700,000	50,000,000
EPA Consent Decree [Abstract]
Estimate of cost of selective catalytic reduction equipment	225,000,000
Nuclear Decommissioning [Abstract]
Site study frequency	3
Number of nuclear decommissioning phases	2
phase one of nuclear decommissioning plan	1
phase two of nuclear decommissioning plan	2
Estimated decommissioning costs	360,000,000
Previously estimated decommissioning costs	296,200,000
Decommissioning fund deposits	2,800,000	2,900,000	3,200,000
Total Nuclear Decommissioning Trust	185,016,000	175,625,000
Fee for future disposal of spent nuclear fuel	800,000	3,000,000	3,600,000
Nuclear Insurance Industry Aggregate Limit	3,200,000,000
Nuclear Liability Insurance - Full Limit of Public Liability	13,600,000,000
Nuclear Liability Insurance - Maximum Available Commercial Insurance	375,000,000
Nuclear Liability Insurance - Industry-Wide Retrospective Assessment Program	13,200,000,000
Nuclear Liability Insurance - Owners' Insurance Amount Maximum	127,300,000
Nuclear Liability Insurance - Entity Share of Insurance Amount Maximum	59,800,000
Nuclear Liability Insurance - Owners' Insurance Amount, Per Incident	19,000,000
Nuclear Liability Insurance - Entity Share of Insurance Amount, Per Incident	8,900,000
Nuclear Liability Insurance - Owners' Property Insurance, Maximum	2,800,000,000
nuclear liability insurance - owner's property insurance assessment maximum	39,500,000
nuclear liability insurance - equity share, property insurance assessment maximum	18,600,000
Transmission Capacity per Contractual Obligations	306
Net Capacity, in MW	3,092
Cost of Transmission	34,000,000
2011 Through 2015 Generation Capacity Peak Demand [Member]
Renewable Energy Standard [Abstract]
Renewable energy generation capacity, percentage	10.00%
2016 Through 2019 Generation Capacity Peak Demand [Member]
Renewable Energy Standard [Abstract]
Renewable energy generation capacity, percentage	15.00%
2020 And Thereafter Generation Capacity Peak Demand [Member]
Renewable Energy Standard [Abstract]
Renewable energy generation capacity, percentage	20.00%
Uranium Concentrates [Member]
Nuclear Decommissioning [Abstract]
Long-term purchase commitment	27,100,000
Conversion [Member]
Nuclear Decommissioning [Abstract]
Long-term purchase commitment	4,100,000
Enrichment [Member]
Nuclear Decommissioning [Abstract]
Long-term purchase commitment	93,300,000
Fabrication [Member]
Nuclear Decommissioning [Abstract]
Long-term purchase commitment	33,300,000
Coal and Coal Transportation [Member]
Nuclear Decommissioning [Abstract]
Long-term purchase commitment	1,100,000,000
Natural Gas Transportation [Member]
Nuclear Decommissioning [Abstract]
Long-term purchase commitment	$118,500,000
Transmission Service Agreements One [Member]
Nuclear Decommissioning [Abstract]
Net Capacity, in MW	200
Transmission Service Agreements Two [Member]
Nuclear Decommissioning [Abstract]
Net Capacity, in MW	106
Next Year [Member]
Nuclear Decommissioning [Abstract]
Other Commitments [Table Text Block]	68.2
Thereafter [Member]
Nuclear Decommissioning [Abstract]
Other Commitments [Table Text Block]	110

Asset_Retirement_Obligations_D

Asset Retirement Obligations (Details) (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013
Regulatory Liabilities [Line Items]
KGE ownership share	47.00%
Asset Retirement Obligation, Roll Forward Analysis [Roll Forward]
Beginning ARO	$160,682	$152,648
Liabilities settled	-593	-973
Accretion expense	10,316	9,007
Revised ARO estimate	9,580	0
Ending ARO	230,668	160,682
Regulatory liability - removal costs	343,485	329,556
Removal Costs [Member]
Asset Retirement Obligation, Roll Forward Analysis [Roll Forward]
Regulatory liability - removal costs	88,242	114,148
Wolf Creek [Member]
Asset Retirement Obligation, Roll Forward Analysis [Roll Forward]
Revised ARO estimate	$50,683	$0

Common_and_Preferred_Stock_Com

Common and Preferred Stock (Common Stock Details) (USD $)	1 Months Ended	12 Months Ended
In Millions, except Share data, unless otherwise specified	Feb. 28, 2015	Dec. 31, 2014		Dec. 31, 2013		Dec. 31, 2012		Feb. 01, 2015
		months
Common Stock [Line Items]
Common stock, shares authorized		275,000,000		275,000,000		150,000,000
Common stock, shares issued		131,687,454		128,254,229
Forward Sale Agreement, Maximum Amount Authorized		$500
Forward Sale Agreement, Maximum Shares Authorized		25,000,000
Commissions Paid, Percentage of Sales Price of Shares Sold		1.00%
Forward Contract Indexed to Issuer's Equity, Settlement Period		18
Forward Contract Indexed To Issuers Equity, Indexed Shares For Period	200,000	2,892,476	[1]	1,068,112	[1]	0	[1]
Forward Contract Indexed to Issuer's Equity, Estimated Proceeds		$258.30						$7.50
Average forward price of shares		$28.20
Forward Sale Agreement Entered in September Two Thousand And Thriteen [Member]
Common Stock [Line Items]
Forward Contract Indexed to Issuer's Equity, Shares		8,900,000
Commissions Paid, Percentage of Sales Price of Shares Sold		3.50%
Forward Contract Indexed to Issuer's Equity, Settlement Period		24
Shares Borrowed Under Forward Contracts, Price Per Share		$31.15
Forward Sale Agreement Entered in September Two Thousand And Thriteen [Member] | Over Allotment [Member]
Common Stock [Line Items]
Forward Contract Indexed to Issuer's Equity, Shares		900,000
Base Allotment [Member] | Forward Sale Agreement Entered in September Two Thousand And Thriteen [Member]
Common Stock [Line Items]
Forward Contract Indexed to Issuer's Equity, Shares		8,000,000
Direct Stock Purchase Plan And Other Stock-Based Plans [Member]
Common Stock [Line Items]
Common stock, shares issued		500,000		700,000
DSPP [Member]
Common Stock [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Available for Grant		1,600,000		2,000,000
[1]	The shares settled during the years ended December 31, 2014 and 2013, were settled with a physical settlement amount of approximately $82.9 million and $27.0 million, respectively.

Common_and_Preferred_Stock_Pre

Common and Preferred Stock (Preferred Stock Details) (USD $)	12 Months Ended
In Thousands, except Share data, unless otherwise specified	Dec. 31, 2012	Jun. 30, 2012
Preferred Stock, Value, Issued	$21,436	$0
Preferred stock, shares outstanding	214,363
Preferred Stock Redemption Premium	1,131
Total Cost to Redeem	22,567
Redeemable Preferred Stock Rate One [Member]
Preferred Stock, Value, Issued	12,161
Preferred Stock, Dividend Rate, Percentage	4.50%
Preferred stock, shares outstanding	121,613
Preferred Stock Redemption Premium	973
Total Cost to Redeem	13,134
Redeemable Preferred Stock Rate Two [Member]
Preferred Stock, Value, Issued	5,497
Preferred Stock, Dividend Rate, Percentage	4.25%
Preferred stock, shares outstanding	54,970
Preferred Stock Redemption Premium	82
Total Cost to Redeem	5,579
Redeemable Preferred Stock Rate Three [Member]
Preferred Stock, Value, Issued	3,778
Preferred Stock, Dividend Rate, Percentage	5.00%
Preferred stock, shares outstanding	37,780
Preferred Stock Redemption Premium	76
Total Cost to Redeem	$3,854

Common_and_Preferred_Stock_Com1

Common and Preferred Stock Common and Preferred Stock (Schedule of Forward Contracts Indexed to Issuer's Equity) (USD $)	1 Months Ended	12 Months Ended
	Feb. 28, 2015	Dec. 31, 2014		Dec. 31, 2013		Dec. 31, 2012		Feb. 01, 2015	Dec. 31, 2011
Forward Contract Indexed to Issuer's Equity [Line Items]
Stock Issued During Period, Value, New Issues		$87,669,000		$32,906,000		$6,996,000
Forward Sale Agreement, Number of Shares		9,160,500	[1]	12,052,976	[1]	1,753,415	[1]		0
Shares Borrowed Under Forward Contracts		0		11,367,673		1,753,415
Forward Contract Indexed To Issuers Equity, Indexed Shares For Period	200,000	2,892,476	[2]	1,068,112	[2]	0	[2]
Forward Contract Indexed to Issuer's Equity, Estimated Proceeds		258,300,000						7,500,000
Forward Contract Indexed to Issuer's Equity, Forward Rate Per Share		$28.20
Forward Contracts [Member]
Forward Contract Indexed to Issuer's Equity [Line Items]
Stock Issued During Period, Value, New Issues		$82,900,000		$27,000,000
[1]	Assuming physical share settlement of the 9.2 million shares associated with the forward sale transactions that could be settled as of DecemberB 31, 2014, Westar Energy would have received aggregate proceeds of approximately $258.3 million based on a weighted average forward price of $28.20 per share. In February 2015, Westar Energy settled 0.2 million shares with a physical settlement amount of approximately $7.5 million.
[2]	The shares settled during the years ended December 31, 2014 and 2013, were settled with a physical settlement amount of approximately $82.9 million and $27.0 million, respectively.

Variable_Interest_Entities_Nar

Variable Interest Entities (Narrative) (Details) (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013
Variable Interest Entity [Line Items]
Noncontrolling Interest, Decrease from Deconsolidation	$7,342	$14,282
Jeffrey Energy Center [Member]
Variable Interest Entity [Line Items]
Variable Interest Entity Percentage of Asset Held	8.00%
Agreement expiration date	31-Jan-19
La Cygne Generating Station [Member]
Variable Interest Entity [Line Items]
Variable Interest Entity Percentage of Asset Held	50.00%
Agreement expiration date	30-Sep-29
Railroad Transportation Equipment [Member]
Variable Interest Entity [Line Items]
Agreement expiration date	31-May-13
Noncontrolling Interest, Decrease from Deconsolidation	14,300
Railroad Transportation Equipment 2 [Member]
Variable Interest Entity [Line Items]
Agreement expiration date	30-Nov-14
Noncontrolling Interest, Decrease from Deconsolidation	$7,300

Variable_Interest_Entities_Ass

Variable Interest Entities (Assets And Liabilities In Relation To VIEs) (Details) (USD $)	Dec. 31, 2014		Dec. 31, 2013
In Thousands, unless otherwise specified
Variable Interest Entity [Line Items]
Property, plant and equipment, net	$8,162,908		$7,551,916
Regulatory Assets	859,778		755,414
Current maturities of long-term debt	0		250,000
Accrued interest	79,707		80,457
Long-term debt, net	3,215,539		2,968,958
Variable Interest Entity, Primary Beneficiary [Member]
Variable Interest Entity [Line Items]
Property, plant and equipment, net	278,573		296,626
Regulatory Assets	7,882	[1]	6,792	[1]
Current maturities of long-term debt	27,933		27,479
Accrued interest	2,961	[2]	3,472	[2]
Long-term debt, net	$166,565		$194,802
[1]	(a) Included in long-term regulatory assets on our consolidated balance sheets.(b) Included in accrued interest on our consolidated balance sheets.
[2]	Included in accrued interest on our consolidated balance sheets.

Leases_Details

Leases (Details) (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013
	Y
Minimum [Member]
Leases [Line Items]
Lease term in years	1
Maximum [Member]
Leases [Line Items]
Lease term in years	20
Vehicles [Member]
Leases [Line Items]
Capital leased assets gross	18,819	$12,141
Vehicles [Member] | Minimum [Member]
Leases [Line Items]
Lease term in years	2
Vehicles [Member] | Maximum [Member]
Leases [Line Items]
Lease term in years	8
Computer Equipment [Member]
Leases [Line Items]
Capital leased assets gross	1,504	$1,758
Computer Equipment [Member] | Minimum [Member]
Leases [Line Items]
Lease term in years	3
Computer Equipment [Member] | Maximum [Member]
Leases [Line Items]
Lease term in years	5

Leases_Leases_Operating_Leases

Leases Leases (Operating Leases, Minimum Annual Rental Payments) (Details) (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Rental expense:
Rental expense	$14,143	$16,484	$17,080
Future commitments:
2013	12,396
2014	10,434
2015	8,560
2016	7,148
2017	5,930
Thereafter	9,115
Total future commitments	$53,583

Leases_Assets_Recorded_Under_C

Leases (Assets Recorded Under Capital Leases) (Details) (USD $)	Dec. 31, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Leases [Line Items]
Accumulated amortization	($11,741)	($10,493)
Total capital leases	48,631	51,752
Vehicles [Member]
Leases [Line Items]
Capital leased assets gross	18,819	12,141
Computer Equipment [Member]
Leases [Line Items]
Capital leased assets gross	1,504	1,758
Generation Plant [Member]
Leases [Line Items]
Capital leased assets gross	$40,049	$48,346

Leases_Capital_Leases_Minimum_

Leases (Capital Leases, Minimum Annual Rental Payments) (Details) (USD $)	Dec. 31, 2014
In Thousands, unless otherwise specified
Leases [Abstract]
2013	$6,379
2014	5,717
2015	5,284
2016	5,131
2017	4,493
Thereafter	59,660
Total future commitments	86,664
Amounts representing imputed interest	-34,922
Present value of net minimum lease payments under capital leases	51,742
Less: current portion	3,833
Total long-term obligation under capital leases	$47,909

Quarterly_Results_Unaudited_De

Quarterly Results (Unaudited) (Details) (USD $)	3 Months Ended																12 Months Ended
In Thousands, except Per Share data, unless otherwise specified	Dec. 31, 2014		Sep. 30, 2014		Jun. 30, 2014		Mar. 31, 2014		Dec. 31, 2013		Sep. 30, 2013		Jun. 30, 2013		Mar. 31, 2013		Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Quarterly Results [Line Items]
Revenues	$596,439	[1]	$764,040	[1]	$612,668	[1]	$628,556	[1]	$559,878	[1]	$694,974	[1]	$569,589	[1]	$546,212	[1]	$2,601,703	$2,370,654	$2,261,470
Net income	45,773	[1]	149,760	[1]	55,822	[1]	70,970	[1]	43,061	[1]	135,095	[1]	69,451	[1]	53,256	[1]	322,325	300,863	282,462
Net Income attributable to common stock	$43,449	[1]	$147,382	[1]	$53,473	[1]	$68,955	[1]	$41,062	[1]	$133,125	[1]	$67,188	[1]	$51,144	[1]	$313,259	$292,520	$273,530
Basic: Earnings available	$0.33	[1]	$1.13	[1]	$0.41	[1]	$0.53	[1]	$0.32	[1]	$1.04	[1]	$0.53	[1]	$0.40	[1]	$2.40	$2.29	$2.15
Diluted: Earnings available	$0.32	[1]	$1.10	[1]	$0.40	[1]	$0.52	[1]	$0.32	[1]	$1.04	[1]	$0.52	[1]	$0.40	[1]	$2.35	$2.27	$2.15
Cash dividend declared per common share	$0.35	[1]	$0.35	[1]	$0.35	[1]	$0.35	[1]	$0.34	[1]	$0.34	[1]	$0.34	[1]	$0.34	[1]	$1.40	$1.36	$1.32
High [Member]
Quarterly Results [Line Items]
Market price per common share	$43.15	[1]	$38.23	[1]	$38.24	[1]	$35.33	[1]	$32.56	[1]	$34.31	[1]	$34.96	[1]	$33.35	[1]
Low [Member]
Quarterly Results [Line Items]
Market price per common share	$33.73	[1]	$33.76	[1]	$34.51	[1]	$31.67	[1]	$29.95	[1]	$29.79	[1]	$30.13	[1]	$28.59	[1]
[1]	(a)Items are computed independently for each of the periods presented and the sum of the quarterly amounts may not equal the total for the year.

Valuation_and_Qualifying_Accou1

Valuation and Qualifying Accounts (Details) (Allowance for Doubtful Accounts [Member], USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013		Dec. 31, 2012
Allowance for Doubtful Accounts [Member]
Movement in Valuation Allowances and Reserves [Roll Forward]
Balance at Beginning of Period	$4,596	$4,916		$7,384
Charged to Costs and Expenses	9,752	7,039		6,617
Deductions	-9,039	-7,359	[1]	-9,085	[1]
Balance at End of Period	$5,309	$4,596		$4,916
[1]	Result from write-offs of accounts receivable.