CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (USD $) In Thousands, except Share data, unless otherwise specified	3 Months Ended				6 Months Ended
	Jun. 30, 2012		Jun. 30, 2011		Jun. 30, 2012	Jun. 30, 2011
OPERATING REVENUES:
OPERATING REVENUES	$ 740,698		$ 674,931		$ 1,352,118	$ 1,315,914
Operating Expenses
Fuel for power generation	112,585		156,803		229,620	303,141
Purchased power	164,092		160,308		281,208	295,324
Gas purchased for resale	9,492		24,984		41,109	77,616
Deferred energy	10,490		(8,106)		(1,249)	(10,058)
Energy efficiency program costs	24,600		0		44,025	0
Other operating expenses	103,371		97,547		206,972	203,521
Maintenance	24,650		32,186		57,176	61,948
Depreciation and amortization	96,316		89,606		187,178	172,708
Taxes other than income	14,266		14,684		28,775	30,929
Total Operating Expenses	559,862		568,012		1,074,814	1,135,129
OPERATING INCOME	180,836		106,919		277,304	180,785
OTHER INCOME (EXPENSE):
Interest expense (net of AFUDC-debt)	(74,564)		(80,879)		(152,495)	(158,222)
Interest income (expense) on regulatory items	(1,977)		(1,379)		(4,179)	(2,267)
AFUDC - equity	2,319		3,522		4,251	11,164
Other income	6,291		1,756		10,485	4,740
Other expense	(4,640)		(9,087)		(7,700)	(13,743)
Total Other Income (Expense)	(72,571)		(86,067)		(149,638)	(158,328)
Income Before Income Tax Expense	108,265		20,852		127,666	22,457
Income Tax Expense (Benefit)	38,826		7,964		46,054	7,239
NET INCOME	69,439		12,888		81,612	15,218
Other comprehensive income (loss):
Change in compensation retirement benefits liability and amortization	154		731		309	1,873
Change in market value of risk management assets and liabilities	(229)		0		(475)	0
OTHER COMPREHENSIVE INCOME(LOSS)	(75)		731		(166)	1,873
COMPREHENSIVE INCOME	69,364		13,619		81,446	17,091
Amount per share basic and diluted
Net income per share - basic	$ 0.29		$ 0.05		$ 0.35	$ 0.06
Net income per share - diluted	$ 0.29		$ 0.05		$ 0.34	$ 0.06
Weighted Average Shares of Common Stock Outstanding - basic	235,999,750		235,867,068		235,999,750	235,697,687
Weighted Average Shares of Common Stock Outstanding - diluted	237,903,276	[1]	237,278,546	[1]	237,715,070	237,027,656
Dividends Declared Per Share of Common Stock	$ 0.17		$ 0.12		$ 0.30	$ 0.24
NPC [Member]
OPERATING REVENUES:
OPERATING REVENUES	553,143		473,898		948,831	863,966
Operating Expenses
Fuel for power generation	81,258		114,744		161,807	215,814
Purchased power	135,276		122,408		216,807	217,974
Deferred energy	5,053		2,350		7,224	9,080
Energy efficiency program costs	21,200		0		36,974	0
Other operating expenses	68,650		61,935		135,112	127,036
Maintenance	16,988		19,325		40,061	41,662
Depreciation and amortization	69,131		61,913		134,121	119,586
Taxes other than income	8,596		9,046		17,050	19,104
Total Operating Expenses	406,152		391,721		749,156	750,256
OPERATING INCOME	146,991		82,177		199,675	113,710
OTHER INCOME (EXPENSE):
Interest expense (net of AFUDC-debt)	(52,602)		(55,736)		(107,007)	(107,769)
Interest income (expense) on regulatory items	(1,849)		126		(3,865)	761
AFUDC - equity	1,577		2,855		2,990	9,953
Other income	5,392		568		7,101	2,114
Other expense	(2,993)		(5,179)		(4,339)	(7,911)
Total Other Income (Expense)	(50,475)		(57,366)		(105,120)	(102,852)
Income Before Income Tax Expense	96,516		24,811		94,555	10,858
Income Tax Expense (Benefit)	34,219		8,748		33,574	3,815
NET INCOME	62,297		16,063		60,981	7,043
Other comprehensive income (loss):
Change in compensation retirement benefits liability and amortization	64		200		127	953
COMPREHENSIVE INCOME	62,361		16,263		61,108	7,996
SPPC [Member]
OPERATING REVENUES:
Electric	168,007		164,582		337,813	343,199
Gas	19,544		36,448		65,466	108,742
OPERATING REVENUES	187,551		201,030		403,279	451,941
Operating Expenses
Fuel for power generation	31,327		42,059		67,813	87,327
Purchased power	28,816		37,900		64,401	77,350
Gas purchased for resale	9,492		24,984		41,109	77,616
Deferral of energy - electric-net	4,314		(11,898)		(8,356)	(23,829)
Deferral of energy - gas-net	1,123		1,442		(117)	4,691
Energy efficiency program costs	3,400		0		7,051	0
Other operating expenses	33,654		34,687		70,086	74,903
Maintenance	7,662		12,861		17,115	20,286
Depreciation and amortization	27,185		27,693		53,057	53,122
Taxes other than income	5,625		5,599		11,488	11,623
Total Operating Expenses	152,598		175,327		323,647	383,089
OPERATING INCOME	34,953		25,703		79,632	68,852
OTHER INCOME (EXPENSE):
Interest expense (net of AFUDC-debt)	(15,379)		(16,774)		(32,352)	(33,720)
Interest income (expense) on regulatory items	(128)		(1,505)		(314)	(3,028)
AFUDC - equity	742		667		1,261	1,211
Other income	599		602		2,782	1,866
Other expense	(1,276)		(3,554)		(2,611)	(5,148)
Total Other Income (Expense)	(15,442)		(20,564)		(31,234)	(38,819)
Income Before Income Tax Expense	19,511		5,139		48,398	30,033
Income Tax Expense (Benefit)	6,832		1,627		17,075	9,945
NET INCOME	12,679		3,512		31,323	20,088
Other comprehensive income (loss):
Change in compensation retirement benefits liability and amortization	43		390		85	1,951
COMPREHENSIVE INCOME	$ 12,722		$ 3,902		$ 31,408	$ 22,039

[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, 435,872 and 451,028 shares, would be included for the three and six months ended June 30, 2012, respectively, and 572,957 and 577,357 would be included for the three and six months ended June 30, 2011, respectively.