DEBT COVENANT AND OTHER RESTRICTIONS, Ability to Issue Debt (Details) (USD $)	12 Months Ended
	Dec. 31, 2012
Ability to issue debt [Abstract]
Covenant terms	maintain a ratio of total consolidated indebtedness to total consolidated capitalization, determined on the last day of each fiscal quarter, not to exceed 0.70 to 1.00 and a fixed charge covenant that requires NVE not to permit the fixed charge coverage ratio, determined on the last day of each fiscal quarter, to be less than 1.50 to 1.00
Maximum additional indebtedness the entity is allowed to incur under covenant	$ 3,300,000,000
Nevada Power Company [Member] | Financing Authority from PUCN [Member]
Ability to issue debt [Abstract]
Maximum additional indebtedness the entity is allowed to incur under covenant	725,000,000
Maximum amount of refinancing of long-term debt securities	322,500,000
Nevada Power Company [Member] | Financing Authority from PUCN [Member] | Line of Credit [Member]
Ability to issue debt [Abstract]
Maximum amount of credit facility the entity has authority to maintain	1,300,000,000
Nevada Power Company [Member] | Financial Covenants Within Financing Agreements [Member] | Line of Credit [Member]
Ability to issue debt [Abstract]
Covenant terms	maintain a ratio of consolidated indebtedness to consolidated capital, determined as of the last day of each fiscal quarter, not to exceed 0.68 to 1
Maximum additional indebtedness the entity is allowed to incur under covenant	2,900,000,000
Nevada Power Company [Member] | Indenture [Member] | Secured Debt [Member]
Ability to issue debt [Abstract]
Maximum additional indebtedness the entity is allowed to incur under covenant	1,600,000,000
Amount of secured debt outstanding	3,800,000,000
Percent of net utility property additions on which capacity to issue additional debt is based (in hundredths)	70.00%
Sierra Pacific Power Company [Member] | Financing Authority from PUCN [Member]
Ability to issue debt [Abstract]
Maximum additional indebtedness the entity is allowed to incur under covenant	350,000,000
Maximum amount of refinancing of long-term debt securities	348,000,000
Sierra Pacific Power Company [Member] | Financing Authority from PUCN [Member] | Line of Credit [Member]
Ability to issue debt [Abstract]
Maximum amount of credit facility the entity has authority to maintain	600,000,000
Sierra Pacific Power Company [Member] | Financial Covenants Within Financing Agreements [Member] | Line of Credit [Member]
Ability to issue debt [Abstract]
Covenant terms	maintain a ratio of consolidated indebtedness to consolidated capital, determined as of the last day of each fiscal quarter, not to exceed 0.68 to 1
Maximum additional indebtedness the entity is allowed to incur under covenant	1,000,000,000
Sierra Pacific Power Company [Member] | Indenture [Member] | Secured Debt [Member]
Ability to issue debt [Abstract]
Maximum additional indebtedness the entity is allowed to incur under covenant	824,000,000
Amount of secured debt outstanding	$ 1,500,000,000
Percent of net utility property additions on which capacity to issue additional debt is based (in hundredths)	70.00%