CONSOLIDATED STATEMENTS OF CASH FLOWS (USD $) In Thousands, unless otherwise specified	9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012
CASH FLOWS FROM OPERATING ACTIVITIES:
Net Income	$ 271,942	$ 304,782
Adjustments to Reconcile Net Income (Loss) to Cash Provided by (Used in) Operating Activities [Abstract]
Depreciation, Depletion and Amortization, Nonproduction	291,687	281,690
Deferred Income Taxes and Tax Credits	152,280	187,229
Public Utilities, Allowance for Funds Used During Construction, Capitalized Cost of Equity	(7,730)	(6,666)
Deferred energy	(218,156)	(18,702)
Non Cash Regulatory Disallowance	17,335	0
Amortization of other regulatory assets	134,846	114,626
Deferred rate increase	9,241	2,252
Other Noncash Income (Expense)	3,649	(50,012)
Changes in certain assets and liabilities:
Accounts receivable	(101,079)	(151,420)
Materials, supplies and fuel	16,909	(18,034)
Other current assets	(8,292)	(10,390)
Accounts payable	7,042	22,646
Increase (Decrease) in Pension and Postretirement Obligations	(17,563)	(12,946)
Other current liabilities	(594)	(23,643)
Other deferred assets	(3,634)	(3,572)
Other regulatory assets	(3,276)	34,420
Other deferred liabilities	9,099	(8,066)
Net Cash from Operating Activities	553,706	644,194
CASH FLOWS USED BY INVESTING ACTIVITIES:
Additions to utility plant (excluding AFUDC-equity)	(267,798)	(387,790)
Customer advances for construction	921	(1,508)
Contributions in aid of construction	38,714	63,864
Investments and other property - net	(5,144)	217
Net Cash Provided by (Used in) Investing Activities	(233,307)	(325,217)
CASH FLOWS FROM FINANCING ACTIVITIES:
Proceeds from issuance of long-term debt	247,245	130,764
Retirement of long-term debt	(354,443)	(272,353)
Sale of Common Stock	2,133	0
Common stock repurchased	(6,329)	(4,509)
Dividends paid	(134,250)	(110,920)
Net Cash from/(used by) Financing Activities	(245,644)	(257,018)
Net Increase (Decrease) in Cash and Cash Equivalents	74,755	61,959
Beginning Balance in Cash and Cash Equivalents	298,271	145,944
Ending Balance in Cash and Cash Equivalents	373,026	207,903
Cash paid during period for:
Interest	233,502	237,262
Income taxes	2	151
Noncash Investing and Financing Items [Abstract]
Noncash or Part Noncash Acquisition, Fixed Assets Acquired	141,214	132,112
Issuance of treasury stock	13,102	0
Nevada Power Company
CASH FLOWS FROM OPERATING ACTIVITIES:
Net Income	228,552	256,151
Adjustments to Reconcile Net Income (Loss) to Cash Provided by (Used in) Operating Activities [Abstract]
Depreciation, Depletion and Amortization, Nonproduction	207,915	201,096
Deferred Income Taxes and Tax Credits	126,080	150,289
Public Utilities, Allowance for Funds Used During Construction, Capitalized Cost of Equity	(6,151)	(4,823)
Deferred energy	(152,534)	(7,335)
Non Cash Regulatory Disallowance	11,866	0
Amortization of other regulatory assets	75,893	56,012
Deferred rate increase	9,241	2,252
Other Noncash Income (Expense)	(722)	(35,553)
Changes in certain assets and liabilities:
Accounts receivable	(118,863)	(164,858)
Materials, supplies and fuel	7,017	(5,119)
Other current assets	(7,222)	(3,715)
Accounts payable	20,856	53,985
Increase (Decrease) in Pension and Postretirement Obligations	3,048	3,708
Other current liabilities	(5,819)	(25,246)
Other deferred assets	(1,613)	(2,412)
Other regulatory assets	26	50,008
Other deferred liabilities	1,613	(10,412)
Net Cash from Operating Activities	399,183	514,028
CASH FLOWS USED BY INVESTING ACTIVITIES:
Additions to utility plant (excluding AFUDC-equity)	(159,063)	(232,608)
Customer advances for construction	1,035	713
Contributions in aid of construction	20,263	34,274
Investments and other property - net	1,595	193
Net Cash Provided by (Used in) Investing Activities	(136,170)	(197,428)
CASH FLOWS FROM FINANCING ACTIVITIES:
Proceeds from issuance of long-term debt	(261)	132,259
Retirement of long-term debt	(103,718)	(271,241)
Dividends paid	(105,000)	(119,000)
Net Cash from/(used by) Financing Activities	(208,979)	(257,982)
Net Increase (Decrease) in Cash and Cash Equivalents	54,034	58,618
Beginning Balance in Cash and Cash Equivalents	201,202	65,887
Ending Balance in Cash and Cash Equivalents	255,236	124,505
Cash paid during period for:
Interest	174,050	177,459
Income taxes	1	1
Noncash Investing and Financing Items [Abstract]
Noncash or Part Noncash Acquisition, Fixed Assets Acquired	119,943	111,052
Sierra Pacific Power Company
CASH FLOWS FROM OPERATING ACTIVITIES:
Net Income	61,931	65,750
Adjustments to Reconcile Net Income (Loss) to Cash Provided by (Used in) Operating Activities [Abstract]
Depreciation, Depletion and Amortization, Nonproduction	83,772	80,594
Deferred Income Taxes and Tax Credits	32,847	42,809
Public Utilities, Allowance for Funds Used During Construction, Capitalized Cost of Equity	(1,579)	(1,843)
Deferred energy	(65,622)	(11,367)
Non Cash Regulatory Disallowance	5,469	0
Amortization of other regulatory assets	58,769	58,484
Other Noncash Income (Expense)	185	(15,532)
Changes in certain assets and liabilities:
Accounts receivable	17,700	13,452
Materials, supplies and fuel	9,892	(12,915)
Other current assets	(934)	(6,512)
Accounts payable	(16,893)	(21,002)
Increase (Decrease) in Pension and Postretirement Obligations	(23,544)	(18,477)
Other current liabilities	2,141	(3,522)
Other deferred assets	(2,021)	(1,160)
Other regulatory assets	(3,302)	(15,588)
Other deferred liabilities	(1,876)	(6,282)
Net Cash from Operating Activities	156,935	146,889
CASH FLOWS USED BY INVESTING ACTIVITIES:
Additions to utility plant (excluding AFUDC-equity)	(108,735)	(155,182)
Customer advances for construction	(114)	(2,221)
Contributions in aid of construction	18,451	29,590
Investments and other property - net	24	24
Net Cash Provided by (Used in) Investing Activities	(90,374)	(127,789)
CASH FLOWS FROM FINANCING ACTIVITIES:
Proceeds from issuance of long-term debt	247,506	(1,447)
Retirement of long-term debt	(250,725)	(1,112)
Dividends paid	(40,000)	(20,000)
Net Cash from/(used by) Financing Activities	(43,219)	(22,559)
Net Increase (Decrease) in Cash and Cash Equivalents	23,342	(3,459)
Beginning Balance in Cash and Cash Equivalents	60,786	55,195
Ending Balance in Cash and Cash Equivalents	84,128	51,736
Cash paid during period for:
Interest	45,554	45,772
Noncash Investing and Financing Items [Abstract]
Noncash or Part Noncash Acquisition, Fixed Assets Acquired	$ 21,271	$ 21,060