REGULATORY ACTIONS, Summary of Regulatory Actions (Details) (USD $)	3 Months Ended			9 Months Ended
	Sep. 30, 2013		Sep. 30, 2012	Sep. 30, 2013		Sep. 30, 2012
Energy And Gas Related Regulatory Filings [Abstract]
Regulatory Disallowances	$ 17,335,000		$ 0	$ 17,335,000		$ 0
Nevada Power Company
Revenue Requirement Subject To Change:
Authorized Revenue Requirement	58,000,000			58,000,000
Present Revenue Requirement	117,500,000			117,500,000
$ Change in Revenue Requirement	(59,500,000)			(59,500,000)
Energy And Gas Related Regulatory Filings [Abstract]
Regulatory Disallowances	11,866,000		0	11,866,000		0
Nevada Power Company | DEAA [Member]
Energy And Gas Related Regulatory Filings [Abstract]
Regulatory Disallowances	1,100,000			1,100,000
Nevada Power Company | REPR [Member]
Revenue Requirement Subject To Change:
Effective Date				Oct. 2013	[1]
Authorized Revenue Requirement	28,400,000	[1]		28,400,000	[1]
Present Revenue Requirement	38,700,000	[1]		38,700,000	[1]
$ Change in Revenue Requirement	(10,300,000)	[1]		(10,300,000)	[1]
Nevada Power Company | TRED [Member]
Revenue Requirement Subject To Change:
Effective Date				Oct. 2013	[1]
Authorized Revenue Requirement	15,700,000	[1]		15,700,000	[1]
Present Revenue Requirement	15,900,000	[1]		15,900,000	[1]
$ Change in Revenue Requirement	(200,000)	[1]		(200,000)	[1]
Nevada Power Company | EEPR Base [Member]
Revenue Requirement Subject To Change:
Effective Date				Oct. 2013	[1]
Authorized Revenue Requirement	45,900,000	[1]		45,900,000	[1]
Present Revenue Requirement	32,600,000	[1]		32,600,000	[1]
$ Change in Revenue Requirement	13,300,000	[1]		13,300,000	[1]
Nevada Power Company | EEPR Amortization [Member]
Revenue Requirement Subject To Change:
Effective Date				Oct. 2013	[1]
Authorized Revenue Requirement	(29,900,000)	[1]		(29,900,000)	[1]
Present Revenue Requirement	9,000,000	[1]		9,000,000	[1]
$ Change in Revenue Requirement	(38,900,000)	[1]		(38,900,000)	[1]
Nevada Power Company | EEIR Base [Member]
Revenue Requirement Subject To Change:
Effective Date				Oct. 2013	[2]
Authorized Revenue Requirement	15,100,000	[2]		15,100,000	[2]
Present Revenue Requirement	10,600,000	[2]		10,600,000	[2]
$ Change in Revenue Requirement	4,500,000	[2]		4,500,000	[2]
Nevada Power Company | EEIR Amortization [Member]
Revenue Requirement Subject To Change:
Effective Date				Oct. 2013	[3]
Authorized Revenue Requirement	(17,200,000)	[3]		(17,200,000)	[3]
Present Revenue Requirement	10,700,000	[3]		10,700,000	[3]
$ Change in Revenue Requirement	(27,900,000)	[3]		(27,900,000)	[3]
Energy And Gas Related Regulatory Filings [Abstract]
Regulatory Disallowances	10,800,000			10,800,000
Regulatory reserve	11,200,000			11,200,000
Sierra Pacific Power Company
Energy And Gas Related Regulatory Filings [Abstract]
Regulatory Disallowances	5,469,000		0	5,469,000		0
SPPC Electric
Energy And Gas Related Regulatory Filings [Abstract]
Regulatory Disallowances	5,469,000			5,469,000
SPPC Electric | GRC [Member]
Revenue Requirement Subject To Change:
Effective Date				January 1, 2014
SPPC Electric | Sierra Pacific Power Company
Revenue Requirement Subject To Change:
Authorized Revenue Requirement	55,400,000			55,400,000
Present Revenue Requirement	64,700,000			64,700,000
$ Change in Revenue Requirement	(9,300,000)			(9,300,000)
SPPC Electric | Sierra Pacific Power Company | DEAA [Member]
Energy And Gas Related Regulatory Filings [Abstract]
Regulatory Disallowances	100,000			100,000
SPPC Electric | Sierra Pacific Power Company | REPR [Member]
Revenue Requirement Subject To Change:
Effective Date				Oct. 2013	[1]
Authorized Revenue Requirement	42,300,000	[1]		42,300,000	[1]
Present Revenue Requirement	44,400,000	[1]		44,400,000	[1]
$ Change in Revenue Requirement	(2,100,000)	[1]		(2,100,000)	[1]
SPPC Electric | Sierra Pacific Power Company | TRED [Member]
Revenue Requirement Subject To Change:
Effective Date				Oct. 2013	[1]
Authorized Revenue Requirement	7,400,000	[1]		7,400,000	[1]
Present Revenue Requirement	6,300,000	[1]		6,300,000	[1]
$ Change in Revenue Requirement	1,100,000	[1]		1,100,000	[1]
SPPC Electric | Sierra Pacific Power Company | EEPR Base [Member]
Revenue Requirement Subject To Change:
Effective Date				Oct. 2013	[1]
Authorized Revenue Requirement	6,000,000	[1]		6,000,000	[1]
Present Revenue Requirement	5,600,000	[1]		5,600,000	[1]
$ Change in Revenue Requirement	400,000	[1]		400,000	[1]
SPPC Electric | Sierra Pacific Power Company | EEPR Amortization [Member]
Revenue Requirement Subject To Change:
Effective Date				Oct. 2013	[1]
Authorized Revenue Requirement	(2,100,000)	[1]		(2,100,000)	[1]
Present Revenue Requirement	1,800,000	[1]		1,800,000	[1]
$ Change in Revenue Requirement	(3,900,000)	[1]		(3,900,000)	[1]
SPPC Electric | Sierra Pacific Power Company | EEIR Base [Member]
Revenue Requirement Subject To Change:
Effective Date				Oct. 2013	[4]
Authorized Revenue Requirement	5,500,000	[4]		5,500,000	[4]
Present Revenue Requirement	4,700,000	[4]		4,700,000	[4]
$ Change in Revenue Requirement	800,000	[4]		800,000	[4]
SPPC Electric | Sierra Pacific Power Company | EEIR Amortization [Member]
Revenue Requirement Subject To Change:
Effective Date				Oct. 2013	[3]
Authorized Revenue Requirement	(3,700,000)	[3]		(3,700,000)	[3]
Present Revenue Requirement	1,900,000	[3]		1,900,000	[3]
$ Change in Revenue Requirement	(5,600,000)	[3]		(5,600,000)	[3]
Energy And Gas Related Regulatory Filings [Abstract]
Regulatory Disallowances	5,500,000			5,500,000
Regulatory reserve	4,000,000			4,000,000
SPPC Gas
Revenue Requirement Subject To Change:
$ Change in Revenue Requirement	$ (200,000)			$ (200,000)
SPPC Gas | GRC [Member]
Revenue Requirement Subject To Change:
Effective Date				January 1, 2014

[1] Represents programs that require the Utilities to collect funds from customers for which the related costs are equal to the revenues collected. As a result, such programs have no effect on Operating or Net Income.

[2] The authorized revenue requirement for EEIR Base may be subject to refund based on the PUCN order discussed above if NPC earns in excess of its authorized ROR. In future periods, NPC may record a provision against revenues to the extent its estimated ROR exceeds its authorized ROR.

[3] Amounts related to the EEIR revenue disallowance, discussed above, are required to be refunded back to ratepayers through negative EEIR amortization; however, while these amounts will affect cash flow, they will not have a future impact on revenues, as the disallowance was recognized as of September 30, 2013.

[4] The authorized revenue requirement for EEIR Base may be subject to refund based on the PUCN order discussed above if SPPC earns in excess of its authorized ROR. In future periods, SPPC may record a provision against revenues to the extent its estimated ROR exceeds its authorized ROR.