REGULATORY ACTIONS, Settled Regulatory Actions (Details) (USD $)	Dec. 31, 2010 GRC [Member]	Dec. 31, 2010 NPC [Member]	Dec. 31, 2011 NPC [Member] Mohave Generating Station [Member]	Dec. 31, 2010 NPC [Member] DEAA [Member]	Dec. 31, 2009 NPC [Member] DEAA [Member]	Dec. 31, 2010 NPC [Member] GRC [Member]	Dec. 31, 2008 NPC [Member] GRC [Member]	Dec. 31, 2009 SPPC [Member] DEAA [Member]	Dec. 31, 2010 SPPC [Member] SPPC Gas [Member] DEAA [Member]	Dec. 31, 2009 SPPC [Member] SPPC Gas [Member] DEAA [Member]	Dec. 31, 2010 SPPC [Member] SPPC Electric [Member] DEAA [Member]	Dec. 31, 2009 SPPC [Member] SPPC Electric [Member] DEAA [Member]
Settled Regulatory Actions [Abstract]
DEAA rate (in dollars per kWh)					$ 0.00
Accepted increase (decrease) in general rates						9,200,000			8,300,000		47,000,000	30,800,000
Authorized rate increase (decrease) percentage (in hundredths)	0.41%								4.69%		6.31%	3.19%
Requested rate increase (decrease)					72,100,000					8,700,000		25,900,000
Requested rate increase (decrease) percentage (in hundredths)					3.18%			2.69%		4.71%
Deferred costs refund requested		102,000,000			77,500,000				17,000,000	8,700,000	101,000,000	19,800,000
Amount Of Over Collection Against Deferred Btgr Debit Balance				102,000,000
REPR Revenue Decrease					4,600,000
REPR Revenue Decrease Rate					0.20%
Deferred Base Tariff General Rate balance						95,800,000
Part I Rate Increase							3.00%
GRC Increase Difference Between Billings							9.80%
Mohave Generating Station [Abstract]
Percentage ownership (in hundredths)			14.00%
Mohave Regulatory Asset			12,200,000
Mohave Costs Approved			$ 12,700,000