RETIREMENT PLAN AND POST-RETIREMENT BENEFITS (Tables)

12 Months Ended

Dec. 31, 2011

Compensation and Retirement Disclosure [Abstract]

Schedule of Net Funded Status [Table Text Block]

						Other Postretirement
	Pension Benefits				Benefits
	2011		2010		2011		2010
Change in Benefit Obligations
Benefit obligation at January 1	$	806,034	$	757,748	$	163,423	$	154,287
Service cost		18,427		18,910		2,611		2,466
Interest cost		40,676		42,872		8,360		8,736
Plan participants' contributions		-		-		2,325		1,924
Actuarial loss (gain)		18,552		54,890		(12,525)		9,166
Benefits paid		(42,507)		(58,002)		(12,255)		(12,495)
Plan amendments		577		(10,384)		-		(661)
Special termination benefits		286		-		100		-
Remeasurement adjustment		-		-		-		-
Benefit obligation at December 31	$	842,045	$	806,034	$	152,039	$	163,423
Change in Plan Assets
Fair value of plan net assets at January 1	$	729,940	$	670,794	$	93,648	$	93,298
Actual return on plan assets		78,104		70,838		8,615		10,627
Employer contributions		41,286		41,698		863		294
Plan participants' contributions		-		-		2,325		1,924
Benefits paid		(37,850)		(53,390)		(12,255)		(12,495)
Fair value of plan net assets at December 31	$	811,480	$	729,940	$	93,196	$	93,648
Funded Status at December 31(1)	$	(30,565)	$	(76,094)	$	(58,843)	$	(69,775)

Amounts Recognized in Accumulated Other Comprehensive Income and Regulatory Assets

						Other Postretirement
	Pension Benefits				Benefits
	2011		2010		2011		2010
Net actuarial loss	$	238,672	$	263,015	$	34,501	$	71,650
Prior service credit		(34,730)		(24,343)		(15,141)		(37,149)
Accumulated other comprehensive income, pre-tax		203,942		238,672		19,360		34,501
Regulatory asset for pension plans		(194,936)		(232,717)		(19,360)		(34,501)
Accumulated other comprehensive income, pre-tax, at December 31	$	9,006	$	5,955	$	-	$	-

Amortization of Regulatory Assets for Pension Plans and Accumulated Other Comprehensive Income Into Net Periodic Cost

The estimated amounts that will be amortized from the regulatory assets for pension plans and accumulated other comprehensive income into net periodic cost in 2012 are as follows (dollars in thousands):

			Other
	Pension		Postretirement
	Benefits		Benefits
Actuarial loss	$	13,891	$	2,924
Prior service credit	$	(2,897)	$	(3,947)

Schedule of Accumulated Benefit Obligations in Excess of Fair Value of Plan Assets [Table Text Block]

As of December 31, 2011 and 2010, the projected benefit obligation, accumulated benefit obligation, and fair value of plan net assets for pension plans with a projected benefit obligation in excess of plan net assets, and pension plans with an accumulated benefit obligation in excess of plan assets, were as follows (dollars in thousands):

	2011		2010
Projected benefit obligation, end of year	$	842,045	$	806,034
Accumulated benefit obligation, end of year	$	813,101	$	772,846
Fair value of plan net assets, end of year	$	811,480	$	729,940

Schedule of Allocation of Plan Assets [Table Text Block]

2011 Pension Plan Assets

Asset Category			Level 1		Level 2		Level 3		Total
Cash & Cash equivalents(1)			$	4,795	$	39,431	$	-	$	44,226
Equity:
	U.S. Equity Securities(2)			52,204		101,231		-		153,435
	International Equity Securities			110,837		-		-		110,837
Fixed Income:
	U.S. Preferred Securities			64		-		-		64
	International Preferred Securities			842		-		-		842
	U.S. Fixed Income Securities(4)			98,311		339,816		-		438,127
	International Fixed Income Securities			3,135		51,902		-		55,037
Other:
	U.S. Future Contracts			(92)		-		-		(92)
	International Future Contracts			-		-		-		-
	U.S. Convertible Securities			-		-		-		-
	Administrative Trust Net Assets(5)			9,004		-		-		9,004
		Total Pension Plan Assets	$	279,100	$	532,380	$	-	$	811,480

2011 Other Postretirement Benefit Assets
Asset Category			Level 1		Level 2		Level 3		Total
Cash & Cash equivalents(1)			$	105	$	2,756	$	-	$	2,861
Equity:
	U.S. Equity Securities(2)			42,848		2,200		-		45,048
	International Equity Securities			2,409		-		-		2,409
Fixed Income:
	U.S. Preferred Securities			1		-		-		1
	International Preferred Securities			18		-		-		18
	U.S. Fixed Income Securities(4)			10,168		31,301		-		41,469
	International Fixed Income Securities			68		1,128		-		1,196
Other:
	U.S. Future Contracts			(2)		-		-		(2)
	International Future Contracts			-		-		-		-
	U.S. Convertible Securities			-		-		-		-
	Administrative Trust Net Assets(5)			196		-		-		196
		Total Other Postretirement Benefit Assets	$	55,811	$	37,385	$	-	$	93,196

2010 Pension Plan Assets
Asset Category			Level 1		Level 2		Level 3		Total
Cash & Cash equivalents (1)			$	-	$	29,698	$	-	$	29,698
Equity:										-
	U.S. Equity Securities (3)			141,917		(23)		-		141,894
	International Equity Securities			91,631		-		-		91,631
Fixed Income:										-
	U.S. Preferred Securities			59		-		-		59
	International Preferred Securities			-		-		-		-
	U.S. Fixed Income Securities (4)			111,866		326,642		-		438,508
	International Fixed Income Securities			2,784		38,208		-		40,992
Other:										-
	U.S. Future Contracts			35		-		-		35
	International Future Contracts			-		-		-		-
	U.S. Convertible Securities			-		573		-		573
	Administrative Trust Net Liabilities (5)			(13,450)		-		-		(13,450)
		Total Pension Plan Assets	$	334,842	$	395,098	$	-	$	729,940

2010 Other Postretirement Benefit Assets
Asset Category			Level 1		Level 2		Level 3		Total
Cash & Cash equivalents (1)			$	-	$	2,678	$	-	$	2,678
Equity:
	U.S. Equity Securities (3)			50,235		-		-		50,235
	International Equity Securities			2,397		-		-		2,397
Fixed Income:
	U.S. Preferred Securities			2		-		-		2
	International Preferred Securities			-		-		-		-
	U.S. Fixed Income Securities (4)			9,506		28,094		-		37,600
	International Fixed Income Securities			73		999		-		1,072
Other:
	U.S. Future Contracts			1		-		-		1
	International Future Contracts			-		-		-		-
	U.S. Convertible Securities			-		15		-		15
	Administrative Trust Net Liabilities(5)			(352)		-		-		(352)
		Total Other Postretirement Benefit Assets	$	61,862	$	31,786	$	-	$	93,648

Schedule of Assumptions Used [Table Text Block]

The actuarial assumptions used to determine December 31 benefit obligations and net periodic benefit costs were as follows:

	Benefit Obligations			Net Periodic Benefit Costs
	2011		2010	2011	2010
Discount rate-pension	4.91	%	5.09%	5.09%	5.79%
Discount rate-other benefits	5.09	%	5.20%	5.20%	5.75%
Rate of compensation increase	4.00	%	4.00%	4.00%	4.50%
Expected long-term return on plan assets-pension	N/A		N/A	6.75%	6.75%
Expected long-term return on plan assets-other benefits	N/A		N/A	6.75-7.1%	6.75-7.1%
Initial health care cost trend rate	8.00	%	8.00%	8.00%	8.00%
Ultimate health care cost trend rate	4.75	%	4.75%	4.75%	5.00%
Number of years to ultimate trend rate	7		8	8	7

Schedule of Effect of One-Percentage-Point Change in Assumed Health Care Cost Trend Rates [Table Text Block]

Assumed health care cost trend rates have a significant effect on the amounts reported for the health care plans. A one-percentage-point change in assumed health care cost trend rates would have the following effect (dollars in thousands):

	1-Percentage		1-Percentage
	Point Increase		Point Decrease
Effect on the postretirement benefit obligation	$	6,446	$	(5,251)
Effect on total of service and interest cost components	$	696	$	(542)

Schedule of Net Benefit Costs [Table Text Block]

NVE
		Pension Benefits						Other Postretirement Benefits
		2011		2010		2009		2011		2010		2009
Service cost		$	18,427	$	18,910	$	18,837	$	2,611	$	2,466	$	2,421
Interest cost			40,676		42,872		44,145		8,360		8,736		10,072
Expected return on plan assets			(48,767)		(44,275)		(37,159)		(6,386)		(6,223)		(6,048)
Amortization of:
	Prior service (credit)/cost		(2,952)		(1,794)		(1,794)		(3,947)		(3,890)		(1,466)
	Actuarial (gain)/loss		16,620		15,106		27,575		4,333		4,342		5,296
Remeasurement adjustment			-		-		-		-		-		336
Total net benefit cost		$	24,004	$	30,819	$	51,604	$	4,971	$	5,431	$	10,611

NPC
		Pension Benefits						Other Postretirement Benefits
		2011		2010		2009		2011		2010		2009
Service cost		$	9,781	$	9,567	$	9,572	$	1,454	$	1,413	$	1,325
Interest cost			19,521		20,092		21,079		2,459		2,474		2,437
Expected return on plan assets			(24,677)		(21,447)		(17,847)		(2,360)		(2,270)		(2,067)
Amortization of:
	Prior service (credit)/cost		(1,879)		(1,733)		(1,733)		916		946		1,104
	Actuarial (gain)/loss		6,758		7,056		13,192		1,208		1,199		1,272
Remeasurement adjustment			-		-		-		-		-		57
Total net benefit cost		$	9,504	$	13,535	$	24,263	$	3,677	$	3,762	$	4,128

SPPC
		Pension Benefits						Other Postretirement Benefits
		2011		2010		2009		2011		2010		2009
Service cost		$	7,361	$	8,016	$	8,245	$	1,086	$	977	$	1,028
Interest cost			20,050		21,557		21,885		5,830		6,187		7,567
Expected return on plan assets			(22,964)		(21,723)		(18,321)		(3,905)		(3,844)		(3,894)
Amortization of:
	Prior service (credit)/cost		(1,108)		(104)		(104)		(4,878)		(4,851)		(2,586)
	Actuarial (gain)/loss		9,647		7,876		13,701		3,092		3,109		3,990
Remeasurement adjustment			-		-		-		-		-		277
Total net benefit cost		$	12,986	$	15,622	$	25,406	$	1,225	$	1,578	$	6,382

Schedule of Expected Benefit Payments [Table Text Block]

The expected cash flows for the plans, including trust accounts, are as follows (dollars in thousands):

			Other			Expected
	Pension Benefit		Postretirement			Federal
	Payments		Benefit Payments			Subsidy
2012	$	53,237	$	9,569	$	-
2013		57,364		9,736		-
2014		57,264		9,984		-
2015		56,548		10,070		-
2016		63,314		10,173		-
2017-2021		302,569		50,756		-