CONSOLIDATED BALANCE SHEETS (Unaudited) (USD $) In Thousands	Jun. 30, 2011	Dec. 31, 2010
Current Assets:
Cash and cash equivalents	$ 110,736	$ 86,189
Accounts receivable less allowance for uncollectible accounts:	399,798	354,010
Materials, supplies and fuel, at average cost	129,259	114,520
Risk management assets (Note 6)	394	4,007
Current income taxes receivable	82	82
Deferred income taxes	122,455	130,800
Other current assets	37,369	42,330
Total Current Assets	800,093	731,938
Utility Property:
Plant in service	11,914,546	11,068,518
Construction work-in-progress	311,119	908,579
Total	12,225,665	11,977,097
Less accumulated provision for depreciation	3,129,377	3,047,438
Total Utility Property, Net	9,096,288	8,929,659
Investments and other property, net	58,514	61,613
Deferred Charges and Other Assets:
Deferred energy (Note 3)	111,135	117,623
Regulatory assets	1,159,933	1,237,159
Regulatory asset for pension plans	258,350	269,472
Other deferred charges and assets	158,466	166,882
Total Deferred Charges and Other Assets	1,687,884	1,791,136
Assets Held for Sale (Note 10)	0	155,322
TOTAL ASSETS	11,642,779	11,669,668
Current Liabilities:
Current maturities of long-term debt (Note 4)	135,991	355,929
Accounts payable	359,164	346,409
Accrued expenses	124,554	133,851
Risk management liabilities (Note 6)	5,297	33,229
Deferred energy (Note 3)	312,652	315,839
Other current liabilities	66,704	70,638
Total Current Liabilities	1,004,362	1,255,895
Long-term debt (Note 4)	5,151,590	4,924,109
Commitments and Contingencies (Note 8)
Deferred Credits and Other Liabilities:
Deferred income taxes	1,244,182	1,246,410
Deferred investment tax credit	17,369	19,204
Accrued retirement benefits	155,595	148,841
Regulatory liabilities	434,326	428,114
Other deferred credits and liabilities	315,649	265,571
Total Deferred Credits and Other Liabilities	2,167,121	2,108,140
Liabilities Held for Sale (Note 10)	0	30,706
Shareholders' Equity:
Common stock	235,977	235,323
Other paid-in capital	2,713,684	2,705,954
Retained earnings	375,063	416,432
Accumulated other comprehensive loss	(5,018)	(6,891)
Total Shareholders' Equity	3,319,706	3,350,818
TOTAL LIABILITIES AND SHAREHOLDERS' EQUITY	11,642,779	11,669,668
Nevada Power Company [Member]
Current Assets:
Cash and cash equivalents	26,329	60,077
Accounts receivable less allowance for uncollectible accounts:	287,697	224,704
Materials, supplies and fuel, at average cost	66,810	66,459
Risk management assets (Note 6)	372	3,476
Deferred income taxes	74,544	76,282
Other current assets	27,085	29,680
Total Current Assets	482,837	460,678
Utility Property:
Plant in service	8,385,715	7,552,097
Construction work-in-progress	199,625	825,079
Total	8,585,340	8,377,176
Less accumulated provision for depreciation	1,880,362	1,828,366
Total Utility Property, Net	6,704,978	6,548,810
Investments and other property, net	51,981	55,305
Deferred Charges and Other Assets:
Deferred energy (Note 3)	111,135	117,623
Regulatory assets	832,911	871,982
Regulatory asset for pension plans	127,114	133,410
Other deferred charges and assets	116,649	114,016
Total Deferred Charges and Other Assets	1,187,809	1,237,031
TOTAL ASSETS	8,427,605	8,301,824
Current Liabilities:
Current maturities of long-term debt (Note 4)	135,991	355,929
Accounts payable	235,092	232,279
Accounts payable, affiliated companies	47,665	29,334
Accrued expenses	85,380	89,638
Risk management liabilities (Note 6)	4,427	22,764
Deferred energy (Note 3)	182,949	171,349
Other current liabilities	51,454	54,607
Total Current Liabilities	742,958	955,900
Long-term debt (Note 4)	3,465,040	3,221,833
Commitments and Contingencies (Note 8)
Deferred Credits and Other Liabilities:
Deferred income taxes	911,324	908,094
Deferred investment tax credit	6,702	7,255
Accrued retirement benefits	34,564	31,907
Regulatory liabilities	229,552	225,983
Other deferred credits and liabilities	238,837	189,220
Total Deferred Credits and Other Liabilities	1,420,979	1,362,459
Shareholders' Equity:
Common stock	1	1
Other paid-in capital	2,308,219	2,254,219
Retained earnings	493,331	511,288
Accumulated other comprehensive loss	(2,923)	(3,876)
Total Shareholders' Equity	2,798,628	2,761,632
TOTAL LIABILITIES AND SHAREHOLDERS' EQUITY	8,427,605	8,301,824
Sierra Pacific Power Company [Member]
Current Assets:
Cash and cash equivalents	76,093	9,552
Accounts receivable less allowance for uncollectible accounts:	112,041	129,306
Materials, supplies and fuel, at average cost	62,449	48,061
Risk management assets (Note 6)	22	531
Intercompany income taxes receivable	10,351	10,351
Deferred income taxes	60,105	53,282
Other current assets	7,330	11,633
Total Current Assets	328,391	262,716
Utility Property:
Plant in service	3,528,831	3,516,421
Construction work-in-progress	111,494	83,500
Total	3,640,325	3,599,921
Less accumulated provision for depreciation	1,249,015	1,219,072
Total Utility Property, Net	2,391,310	2,380,849
Investments and other property, net	6,181	5,956
Deferred Charges and Other Assets:
Regulatory assets	327,023	365,177
Regulatory asset for pension plans	128,247	131,734
Other deferred charges and assets	34,777	45,268
Total Deferred Charges and Other Assets	490,047	542,179
Assets Held for Sale (Note 10)	0	155,322
TOTAL ASSETS	3,215,929	3,347,022
Current Liabilities:
Accounts payable	89,492	90,206
Accounts payable, affiliated companies	18,295	10,812
Accrued expenses	29,902	33,788
Dividends Declared	0	54,000
Risk management liabilities (Note 6)	870	10,465
Deferred energy (Note 3)	129,703	144,490
Other current liabilities	15,248	16,029
Total Current Liabilities	283,510	359,790
Long-term debt (Note 4)	1,180,051	1,195,775
Commitments and Contingencies (Note 8)
Deferred Credits and Other Liabilities:
Deferred income taxes	410,184	395,454
Deferred investment tax credit	10,667	11,949
Accrued retirement benefits	114,098	110,302
Regulatory liabilities	204,774	202,131
Other deferred credits and liabilities	66,874	67,495
Total Deferred Credits and Other Liabilities	806,597	787,331
Liabilities Held for Sale (Note 10)	0	30,706
Shareholders' Equity:
Common stock	4	4
Other paid-in capital	1,111,574	1,111,262
Retained earnings	(165,138)	(135,226)
Accumulated other comprehensive loss	(669)	(2,620)
Total Shareholders' Equity	945,771	973,420
TOTAL LIABILITIES AND SHAREHOLDERS' EQUITY	$ 3,215,929	$ 3,347,022