CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (USD $) In Thousands, except Share data, unless otherwise specified	3 Months Ended
	Mar. 31, 2012		Mar. 31, 2011
OPERATING REVENUES:
OPERATING REVENUES	$ 611,420		$ 640,983
Operating Expenses
Fuel for power generation	117,035		146,338
Purchased power	117,116		135,016
Gas purchased for resale	31,617		52,632
Deferred energy	(11,739)		(1,952)
Energy efficiency program costs	19,425		0
Other operating expenses	103,601		105,974
Maintenance	32,526		29,762
Depreciation and amortization	90,862		83,102
Taxes other than income	14,509		16,245
Total Operating Expenses	514,952		567,117
OPERATING INCOME	96,468		73,866
OTHER INCOME (EXPENSE):
Interest expense (net of AFUDC-debt)	(77,931)		(77,343)
Interest income (expense) on regulatory items	(2,202)		(888)
AFUDC - equity	1,932		7,642
Other income	4,194		2,984
Other expense	(3,060)		(4,656)
Total Other Income (Expense)	(77,067)		(72,261)
Income Before Income Tax Expense	19,401		1,605
Income Tax Expense (Benefit)	7,228		(725)
NET INCOME	12,173		2,330
Other comprehensive income (loss):
Change in compensation retirement benefits liability and amortization	155		1,142
Change in market value of risk management assets and liabilities	(246)		0
OTHER COMPREHENSIVE INCOME(LOSS)	(91)		1,142
COMPREHENSIVE INCOME	12,082		3,472
Amount per share basic and diluted
Earnings Per Share, Basic and Diluted	$ 0.05		$ 0.01
Net income per share - basic	$ 0.05		$ 0.01
Net income per share - diluted	$ 0.05		$ 0.01
Weighted Average Shares of Common Stock Outstanding - basic	235,999,750		235,526,425
Weighted Average Shares of Common Stock Outstanding - diluted	237,526,863	[1]	236,784,658	[1]
Dividends Declared Per Share of Common Stock	$ 0.13		$ 0.12
NPC [Member]
OPERATING REVENUES:
OPERATING REVENUES	395,688		390,068
Operating Expenses
Fuel for power generation	80,549		101,070
Purchased power	81,531		95,566
Deferred energy	2,171		6,730
Energy efficiency program costs	15,774		0
Other operating expenses	66,462		65,101
Maintenance	23,073		22,337
Depreciation and amortization	64,990		57,673
Taxes other than income	8,454		10,058
Total Operating Expenses	343,004		358,535
OPERATING INCOME	52,684		31,533
OTHER INCOME (EXPENSE):
Interest expense (net of AFUDC-debt)	(54,405)		(52,033)
Interest income (expense) on regulatory items	(2,016)		635
AFUDC - equity	1,413		7,098
Other income	1,709		1,546
Other expense	(1,346)		(2,732)
Total Other Income (Expense)	(54,645)		(45,486)
Income Before Income Tax Expense	(1,961)		(13,953)
Income Tax Expense (Benefit)	(645)		(4,933)
NET INCOME	(1,316)		(9,020)
Other comprehensive income (loss):
Change in compensation retirement benefits liability and amortization	63		753
COMPREHENSIVE INCOME	(1,253)		(8,267)
SPPC [Member]
OPERATING REVENUES:
Electric	169,806		178,617
Gas	45,922		72,294
OPERATING REVENUES	215,728		250,911
Operating Expenses
Fuel for power generation	36,486		45,268
Purchased power	35,585		39,450
Gas purchased for resale	31,617		52,632
Deferral of energy - electric-net	(12,670)		(11,931)
Deferral of energy - gas-net	(1,240)		3,249
Energy efficiency program costs	3,651		0
Other operating expenses	36,432		40,216
Maintenance	9,453		7,425
Depreciation and amortization	25,872		25,429
Taxes other than income	5,863		6,024
Total Operating Expenses	171,049		207,762
OPERATING INCOME	44,679		43,149
OTHER INCOME (EXPENSE):
Interest expense (net of AFUDC-debt)	(16,973)		(16,946)
Interest income (expense) on regulatory items	(186)		(1,523)
AFUDC - equity	519		544
Other income	2,183		1,264
Other expense	(1,335)		(1,594)
Total Other Income (Expense)	(15,792)		(18,255)
Income Before Income Tax Expense	28,887		24,894
Income Tax Expense (Benefit)	10,243		8,318
NET INCOME	18,644		16,576
Other comprehensive income (loss):
Change in compensation retirement benefits liability and amortization	42		1,561
COMPREHENSIVE INCOME	$ 18,686		$ 18,137

[1] The denominator does not include stock equivalents for options issued under the non-qualified stock option plan due to conversion prices being higher than market prices for all periods. If the conditions for conversion were met under this plan, 466,183 and 581,757 shares would be included for the three months ended March 31, 2012 and 2011, respectively.