REGULATORY ACTIONS, Deferred Energy (Details) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2012		Dec. 31, 2011
Nevada Deferred Energy
Cumulative balance authorized in DEAA	$ (262,845)		$ (334,102)
Amortization	293,185		247,489
Deferred Energy Over Collections	(182,221)	[1]	(173,466)	[2]
Nevada Deferred Energy Balance at period end - Subtotal	(151,881)		(260,079)
Reinstatement of deferred energy (effective 6/07, 10 years)	102,088		117,440
Total Deferred Energy	(49,793)		(142,639)
Deferred Assets
Deferred energy	87,072		102,525
Current Liabilities
Deferred energy (Note 3)	136,865		245,164
NPC Electric [Member]
Nevada Deferred Energy
Cumulative balance authorized in DEAA	(177,336)		(189,032)
Amortization	185,339		120,340
Deferred Energy Over Collections	(109,121)	[1]	(106,022)	[2]
Nevada Deferred Energy Balance at period end - Subtotal	(101,118)		(174,714)
Reinstatement of deferred energy (effective 6/07, 10 years)	102,088		117,440
Total Deferred Energy	970		(57,274)
Deferred Assets
Deferred energy	87,072		102,525
Current Liabilities
Deferred energy (Note 3)	(86,102)		(159,799)
SPPC Electric [Member]
Nevada Deferred Energy
Cumulative balance authorized in DEAA	(56,422)		(115,955)
Amortization	78,601		104,909
Deferred Energy Over Collections	(54,872)	[1]	(45,291)	[2]
Nevada Deferred Energy Balance at period end - Subtotal	(32,693)		(56,337)
Total Deferred Energy	(32,693)		(56,337)
Current Liabilities
Deferred energy (Note 3)	(32,693)		(56,337)
SPPC Gas [Member]
Nevada Deferred Energy
Cumulative balance authorized in DEAA	(29,087)		(29,115)
Amortization	29,245		22,240
Deferred Energy Over Collections	(18,228)	[1]	(22,153)	[2]
Nevada Deferred Energy Balance at period end - Subtotal	(18,070)		(29,028)
Total Deferred Energy	(18,070)		(29,028)
Current Liabilities
Deferred energy (Note 3)	$ (18,070)		$ (29,028)

[1] These deferred energy over collections are subject to quarterly rate resets as discussed in Note 1, Summary of Significant Accounting Policies, Deferred Energy Accounting.

[2] Refer to "Settled Regulatory Actions" below for separate discussions regarding NPC and SPPC's 2012 DEAA rate filings.