REGULATORY ACTIONS, Summary of Regulatory Actions (Details) (USD $) In Millions, unless otherwise specified	6 Months Ended
	Jun. 30, 2013
SPPC Gas [Member] | GRC [Member]
Revenue Requirement Subject To Change:
Effective Date	January 1, 2014
SPPC Electric [Member] | GRC [Member]
Revenue Requirement Subject To Change:
Effective Date	January 1, 2014
Nevada Power Company [Member]
Revenue Requirement Subject To Change:
Requested Revenue Requirement	$ 68.5
Present Revenue Requirement	117.5
$ Change in Revenue Requirement	(49.0)
Nevada Power Company [Member] | REPR [Member]
Revenue Requirement Subject To Change:
Effective Date	Oct. 2013	[1]
Requested Revenue Requirement	28.4	[1]
Present Revenue Requirement	38.7	[1]
$ Change in Revenue Requirement	(10.3)	[1]
Nevada Power Company [Member] | TRED [Member]
Revenue Requirement Subject To Change:
Effective Date	Oct. 2013	[1]
Requested Revenue Requirement	15.7	[1]
Present Revenue Requirement	15.9	[1]
$ Change in Revenue Requirement	(0.2)	[1]
Nevada Power Company [Member] | EEPR Base [Member]
Revenue Requirement Subject To Change:
Effective Date	Oct. 2013	[1]
Requested Revenue Requirement	45.9	[1]
Present Revenue Requirement	32.6	[1]
$ Change in Revenue Requirement	13.3	[1]
Nevada Power Company [Member] | EEPR Amortization [Member]
Revenue Requirement Subject To Change:
Effective Date	Oct. 2013	[1]
Requested Revenue Requirement	(29.9)	[1]
Present Revenue Requirement	9.0	[1]
$ Change in Revenue Requirement	(38.9)	[1]
Nevada Power Company [Member] | EEIR Base [Member]
Revenue Requirement Subject To Change:
Effective Date	Oct. 2013
Requested Revenue Requirement	15.1
Present Revenue Requirement	10.6
$ Change in Revenue Requirement	4.5
Nevada Power Company [Member] | EEIR Amortization [Member]
Revenue Requirement Subject To Change:
Effective Date	Oct. 2013
Requested Revenue Requirement	(6.7)
Present Revenue Requirement	10.7
$ Change in Revenue Requirement	(17.4)
Sierra Pacific Power Company [Member] | SPPC Gas [Member]
Revenue Requirement Subject To Change:
Effective Date	October 2013
$ Change in Revenue Requirement	(0.2)
Sierra Pacific Power Company [Member] | SPPC Electric [Member]
Revenue Requirement Subject To Change:
Requested Revenue Requirement	60.2
Present Revenue Requirement	64.7
$ Change in Revenue Requirement	(4.5)
Sierra Pacific Power Company [Member] | SPPC Electric [Member] | REPR [Member]
Revenue Requirement Subject To Change:
Effective Date	Oct. 2013	[1]
Requested Revenue Requirement	42.3	[1]
Present Revenue Requirement	44.4	[1]
$ Change in Revenue Requirement	(2.1)	[1]
Sierra Pacific Power Company [Member] | SPPC Electric [Member] | TRED [Member]
Revenue Requirement Subject To Change:
Effective Date	Oct. 2013	[1]
Requested Revenue Requirement	7.4	[1]
Present Revenue Requirement	6.3	[1]
$ Change in Revenue Requirement	1.1	[1]
Sierra Pacific Power Company [Member] | SPPC Electric [Member] | EEPR Base [Member]
Revenue Requirement Subject To Change:
Effective Date	Oct. 2013	[1]
Requested Revenue Requirement	6.0	[1]
Present Revenue Requirement	5.6	[1]
$ Change in Revenue Requirement	0.4	[1]
Sierra Pacific Power Company [Member] | SPPC Electric [Member] | EEPR Amortization [Member]
Revenue Requirement Subject To Change:
Effective Date	Oct. 2013	[1]
Requested Revenue Requirement	(2.2)	[1]
Present Revenue Requirement	1.8	[1]
$ Change in Revenue Requirement	(4.0)	[1]
Sierra Pacific Power Company [Member] | SPPC Electric [Member] | EEIR Base [Member]
Revenue Requirement Subject To Change:
Effective Date	Oct. 2013
Requested Revenue Requirement	5.6
Present Revenue Requirement	4.7
$ Change in Revenue Requirement	0.9
Sierra Pacific Power Company [Member] | SPPC Electric [Member] | EEIR Amortization [Member]
Revenue Requirement Subject To Change:
Effective Date	Oct. 2013
Requested Revenue Requirement	1.1
Present Revenue Requirement	1.9
$ Change in Revenue Requirement	$ (0.8)

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