CONDENSED CONSOLIDATED BALANCE SHEETS (USD $) In Thousands, unless otherwise specified	Sep. 30, 2013		Dec. 31, 2012
Utility Plant
Plant in Service	$ 5,114,426		$ 5,005,768
Utility Plant Under Capital Leases	621,247		582,669
Construction Work in Progress	211,100		128,621
Total Utility Plant	5,946,773		5,717,058
Less Accumulated Depreciation and Amortization	(1,966,801)		(1,921,733)
Less Accumulated Amortization of Capital Lease Assets	(509,712)		(494,962)
Total Utility Plant—Net	3,470,260		3,300,363
Investments And Other Property
Investments in Lease Equity	36,230		36,339
Other	33,441		36,537
Total Investments and Other Property	69,671		72,876
Current Assets
Cash and Cash Equivalents	72,391		123,918
Accounts Receivable—Customer	127,316		93,742
Unbilled Accounts Receivable	55,730		53,568
Allowance for Doubtful Accounts	(7,215)		(6,545)
Materials and Supplies	89,302		93,322
Fuel Inventory	44,458		62,019
Deferred Income Taxes—Current	66,520		34,260
Regulatory Assets—Current	52,709		51,619
Investments in Lease Debt	0		9,118
Derivative Instruments	1,620		3,165
Other	26,882		33,567
Total Current Assets	529,713		551,753
Regulatory and Other Assets
Regulatory Assets—Noncurrent	200,705	[1]	191,077	[1]
Derivative Instruments	752		3,801
Other Assets	22,704		20,559
Total Regulatory and Other Assets	224,161		215,437
Total Assets	4,293,805		4,140,429
Capitalization
Common Stock Equity	1,132,286		1,065,465
Capital Lease Obligations	130,088		262,138
Long-Term Debt	1,505,536		1,498,442
Total Capitalization	2,767,910		2,826,045
Current Liabilities
Current Obligations Under Capital Leases	169,060		90,583
Borrowings Under Revolving Credit Facilities	23,000		0
Accounts Payable—Trade	91,615		107,740
Accrued Taxes Other than Income Taxes	60,657		41,939
Interest Accrued	22,343		31,950
Accrued Employee Expenses	26,000		24,094
Regulatory Liabilities—Current	56,987	[2]	43,516	[2]
Customer Deposits	30,564		34,048
Derivative Instruments	12,988		14,742
Other	14,521		10,517
Total Current Liabilities	507,735		399,129
Liabilities, Noncurrent [Abstract]
Deferred Tax Liabilities, Net, Noncurrent	482,516		364,756
Regulatory Liability, Noncurrent	297,699	[3]	279,111	[3]
Pension and Other Postretirement Defined Benefit Plans, Liabilities, Noncurrent	141,997		159,401
Derivative Liability, Noncurrent	7,183		12,709
Other Liabilities, Noncurrent	88,765		99,278
Liabilities, Noncurrent	1,018,160		915,255
Commitments and Contingencies
Total Capitalization and Other Liabilities	4,293,805		4,140,429
TUCSON ELECTRIC POWER COMPANY
Utility Plant
Plant in Service	4,434,770		4,348,041
Utility Plant Under Capital Leases	621,247		582,669
Construction Work in Progress	153,258		98,460
Total Utility Plant	5,209,275		5,029,170
Less Accumulated Depreciation and Amortization	(1,811,806)		(1,783,787)
Less Accumulated Amortization of Capital Lease Assets	(509,712)		(494,962)
Total Utility Plant—Net	2,887,757		2,750,421
Investments And Other Property
Investments in Lease Equity	36,230		36,339
Other	32,009		35,091
Total Investments and Other Property	68,239		71,430
Current Assets
Cash and Cash Equivalents	34,786		79,743
Accounts Receivable—Customer	105,646		71,813
Unbilled Accounts Receivable	46,240		33,782
Allowance for Doubtful Accounts	(5,238)		(4,598)
Accounts Receivable, Related Parties, Current	3,963		5,720
Materials and Supplies	76,255		80,377
Fuel Inventory	44,162		61,737
Deferred Income Taxes—Current	69,985		37,212
Regulatory Assets—Current	36,283		34,345	[1]
Investments in Lease Debt	0		9,118
Derivative Instruments	1,047		2,230
Other	20,605		32,163
Total Current Assets	433,734		443,642
Regulatory and Other Assets
Regulatory Assets—Noncurrent	186,626	[1]	178,330	[1]
Derivative Instruments	259		1,354
Other Assets	17,525		15,869
Total Regulatory and Other Assets	204,410		195,553
Total Assets	3,594,140		3,461,046
Capitalization
Common Stock Equity	939,721		860,927
Capital Lease Obligations	130,088		262,138
Long-Term Debt	1,223,536		1,223,442
Total Capitalization	2,293,345		2,346,507
Current Liabilities
Current Obligations Under Capital Leases	169,060		90,583
Accounts Payable—Trade	75,834		82,122
Accounts Payable—Due to Affiliates	2,981		3,134
Accrued Taxes Other than Income Taxes	50,465		33,060
Interest Accrued	20,503		26,965
Accrued Employee Expenses	22,937		20,715
Regulatory Liabilities—Current	26,440	[2]	20,822	[2]
Customer Deposits	21,251		24,846
Derivative Instruments	7,060		4,899
Other	9,336		7,085
Total Current Liabilities	405,867		314,231
Liabilities, Noncurrent [Abstract]
Deferred Tax Liabilities, Net, Noncurrent	421,621		319,216
Regulatory Liability, Noncurrent	259,523	[3]	241,189	[3]
Pension and Other Postretirement Defined Benefit Plans, Liabilities, Noncurrent	132,491		149,718
Derivative Liability, Noncurrent	4,950		10,565
Other Liabilities, Noncurrent	76,343		79,620
Liabilities, Noncurrent	894,928		800,308
Commitments and Contingencies
Total Capitalization and Other Liabilities	$ 3,594,140		$ 3,461,046

[1] Regulatory Assets – Noncurrent increased reflecting a newly created regulatory asset primarily for the investment tax credit basis adjustment. See Note 6. This regulatory asset does not earn a return and will be recovered through future rates. The increase is also related to the addition of deferred rate case costs that do not earn a return and will be recovered over a four year period.

[2] Regulatory Liabilities – Current increased because purchased energy costs are over recovered following deferral of coal costs related to the San Juan mine fire, as discussed above. The regulatory asset related to these deferred costs does not earn a return and will be recovered at the time of the final insurance settlement.

[3] Regulatory Liabilities – Noncurrent increased due to the collection of amounts in rates for future asset removal costs that have not yet been expended.