CONSOLIDATED BALANCE SHEETS (USD $) In Thousands, unless otherwise specified	Sep. 30, 2013	Dec. 31, 2012
Current Assets:
Cash and cash equivalents	$ 373,026	$ 298,271
Accounts receivable less allowance for uncollectible accounts	483,178	373,099
Materials, supplies and fuel, at average cost	121,699	138,337
Deferred energy costs current	82,235	0
Deferred income taxes	120,186	60,592
Other current assets	49,041	40,750
Total Current Assets	1,229,365	911,049
Public Utilities, Property, Plant and Equipment, Net [Abstract]
Plant in service	12,195,312	12,031,053
Construction work-in-progress	821,430	708,109
Total	13,016,742	12,739,162
Less accumulated provision for depreciation	3,526,824	3,313,188
Public Utilities, Property, Plant and Equipment, Net	9,489,918	9,425,974
Investments and other property, net	65,354	56,660
Other Assets, Noncurrent [Abstract]
Deferred Energy Costs Non Current	85,055	87,072
Regulatory assets	1,048,204	1,132,768
Regulatory asset for pension plans	270,565	281,195
Other Assets, Noncurrent	76,705	89,418
Total Deferred Charges and Other Assets	1,480,529	1,590,453
Assets	12,265,166	11,984,136
Current Liabilities:
Current maturities of long-term debt	129,457	356,283
Accounts Payable	316,681	332,245
Accrued expenses	104,781	127,693
Deferred energy	0	136,865
Other current liabilities	88,299	66,221
Total Current Liabilities	639,218	1,019,307
Long-term debt	4,791,809	4,669,798
Commitments and Contingencies
Deferred Credits and Other Liabilities:
Deferred income taxes	1,680,896	1,470,973
Deferred investment tax credit	11,623	13,538
Accrued retirement benefits	144,696	162,260
Regulatory liabilities	631,368	550,687
Other deferred credits and liabilities	656,963	540,202
Total Deferred Credits and Other Liabilities	3,125,546	2,737,660
Shareholders' Equity
Common stock	236,000	236,000
Treasury stock, at cost	(7,898)	(16,804)
Other paid-in capital	2,716,311	2,712,943
Retained earnings	772,995	635,303
Accumulated other comprehensive loss	(8,815)	(10,071)
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest	3,708,593	3,557,371
TOTAL LIABILITIES AND SHAREHOLDERS' EQUITY	12,265,166	11,984,136
Nevada Power Company
Current Assets:
Cash and cash equivalents	255,236	201,202
Accounts receivable less allowance for uncollectible accounts	367,365	248,501
Materials, supplies and fuel, at average cost	70,929	77,675
Deferred energy costs current	68,391	0
Deferred income taxes	80,062	48,590
Other current assets	35,984	28,763
Total Current Assets	877,967	604,731
Public Utilities, Property, Plant and Equipment, Net [Abstract]
Plant in service	8,459,208	8,363,566
Construction work-in-progress	695,749	567,941
Total	9,154,957	8,931,507
Less accumulated provision for depreciation	2,203,320	2,035,322
Public Utilities, Property, Plant and Equipment, Net	6,951,637	6,896,185
Investments and other property, net	51,114	49,808
Other Assets, Noncurrent [Abstract]
Deferred Energy Costs Non Current	84,041	87,072
Regulatory assets	746,286	804,013
Regulatory asset for pension plans	131,628	136,682
Other Assets, Noncurrent	58,097	62,654
Total Deferred Charges and Other Assets	1,020,052	1,090,421
Assets	8,900,770	8,641,145
Current Liabilities:
Current maturities of long-term debt	129,186	106,048
Accounts Payable	202,915	201,193
Accounts Payable, Related Parties, Current	43,800	42,036
Accrued expenses	63,465	86,433
Deferred energy	0	86,102
Other current liabilities	69,479	52,567
Total Current Liabilities	508,845	574,379
Long-term debt	3,103,980	3,230,808
Commitments and Contingencies
Deferred Credits and Other Liabilities:
Deferred income taxes	1,257,818	1,101,804
Deferred investment tax credit	3,857	4,688
Accrued retirement benefits	52,429	49,381
Regulatory liabilities	376,136	323,400
Other deferred credits and liabilities	551,545	434,367
Total Deferred Credits and Other Liabilities	2,241,785	1,913,640
Shareholders' Equity
Common stock	1	1
Other paid-in capital	2,308,211	2,308,211
Retained earnings	742,164	618,612
Accumulated other comprehensive loss	(4,216)	(4,506)
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest	3,046,160	2,922,318
TOTAL LIABILITIES AND SHAREHOLDERS' EQUITY	8,900,770	8,641,145
Sierra Pacific Power Company
Current Assets:
Cash and cash equivalents	84,128	60,786
Accounts receivable less allowance for uncollectible accounts	115,765	124,464
Materials, supplies and fuel, at average cost	50,770	60,662
Deferred energy costs current	13,844	0
Intercompany income taxes receivable	10,351	10,351
Deferred income taxes	49,748	21,589
Other current assets	12,566	11,633
Total Current Assets	337,172	289,485
Public Utilities, Property, Plant and Equipment, Net [Abstract]
Plant in service	3,736,104	3,667,487
Construction work-in-progress	125,681	140,168
Total	3,861,785	3,807,655
Less accumulated provision for depreciation	1,323,504	1,277,866
Public Utilities, Property, Plant and Equipment, Net	2,538,281	2,529,789
Investments and other property, net	7,126	6,499
Other Assets, Noncurrent [Abstract]
Deferred Energy Costs Non Current	1,014	0
Regulatory assets	301,918	328,755
Regulatory asset for pension plans	135,257	140,268
Other Assets, Noncurrent	13,524	21,477
Total Deferred Charges and Other Assets	451,713	490,500
Assets	3,334,292	3,316,273
Current Liabilities:
Current maturities of long-term debt	271	250,235
Accounts Payable	84,277	106,415
Accounts Payable, Related Parties, Current	21,543	21,534
Accrued expenses	29,909	32,936
Deferred energy	0	50,763
Other current liabilities	18,821	13,655
Total Current Liabilities	154,821	475,538
Long-term debt	1,177,829	928,990
Commitments and Contingencies
Deferred Credits and Other Liabilities:
Deferred income taxes	525,694	465,508
Deferred investment tax credit	7,766	8,850
Accrued retirement benefits	75,133	98,676
Regulatory liabilities	255,232	227,287
Other deferred credits and liabilities	76,974	72,688
Total Deferred Credits and Other Liabilities	940,799	873,009
Shareholders' Equity
Common stock	4	4
Other paid-in capital	1,111,266	1,111,266
Retained earnings	(49,055)	(70,986)
Accumulated other comprehensive loss	(1,372)	(1,548)
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest	1,060,843	1,038,736
TOTAL LIABILITIES AND SHAREHOLDERS' EQUITY	$ 3,334,292	$ 3,316,273