SUPPLEMENTAL CASH FLOW INFORMATION - Reconciliation of Net Income to Net Cash Flows from Operating Activities (Detail) (USD $) In Thousands, unless otherwise specified	1 Months Ended	3 Months Ended		9 Months Ended
	Jun. 30, 2013	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Supplemental Cash Flow Information [Line Items]
Net Income		$ 67,990	$ 50,664	$ 113,953	$ 83,414
Adjustments to Reconcile Net Income To Net Cash Flows from Operating Activities
Depreciation Expense		38,204	35,145	111,175	105,319
Amortization of Deferred Charges		5,193	9,069	21,600	26,845
Depreciation and Amortization Recorded to Fuel and Operations and Maintenance Expense				5,399	4,911
Amortization of Deferred Debt-Related Costs Included in Interest Expense				2,280	2,250
Provision for Retail Customer Bad Debts				1,703	2,017
Use of RECs for Compliance				12,999	4,017
Deferred Income Taxes				77,962	63,057
Investment Tax Credit Basis Adjustment	(11,000)			(11,039)	0
Pension and Postretirement Expense				17,087	16,391
Pension and Postretirement Funding				(27,602)	(23,649)
Share-Based Compensation Expense				2,810	1,952
Allowance for Equity Funds Used During Construction				(4,145)	(2,708)
Increase (Decrease) to Reflect PPFAC Recovery		(3,521)	18,076	(6,814)	29,730
PPFAC Reduction - TEP Rate Order				3,000	0
Liquidated Damages				0	1,921
Changes in Assets and Liabilities which Provided (Used) Cash Exclusive of Changes Shown Separately
Accounts Receivable				(32,883)	(28,686)
Materials and Fuel Inventory				14,839	(33,038)
Accounts Payable				(18,497)	(5,220)
Income Taxes				(15,847)	(11,738)
Interest Accrued				(2,137)	(1,551)
Taxes Other Than Income Taxes				18,718	16,478
Other				20,473	16,426
Net Cash Provided by (Used in) Operating Activities				305,034	268,138
TUCSON ELECTRIC POWER COMPANY
Supplemental Cash Flow Information [Line Items]
Net Income		64,167	44,569	96,433	65,018
Adjustments to Reconcile Net Income To Net Cash Flows from Operating Activities
Depreciation Expense		30,311	27,644	87,729	82,656
Amortization of Deferred Charges		6,118	10,001	24,393	29,621
Depreciation and Amortization Recorded to Fuel and Operations and Maintenance Expense				4,602	3,922
Amortization of Deferred Debt-Related Costs Included in Interest Expense				1,831	1,628
Provision for Retail Customer Bad Debts				1,315	1,348
Use of RECs for Compliance				11,766	3,324
Deferred Income Taxes				64,132	51,638
Investment Tax Credit Basis Adjustment	(11,000)			(10,751)	0
Pension and Postretirement Expense				14,909	14,466
Pension and Postretirement Funding				(26,118)	(20,989)
Share-Based Compensation Expense				2,239	1,540
Allowance for Equity Funds Used During Construction				(2,923)	(2,265)
Increase (Decrease) to Reflect PPFAC Recovery		(7,992)	20,025	(5,079)	25,150
PPFAC Reduction - TEP Rate Order	3,000			3,000	0
Liquidated Damages				0	1,921
Changes in Assets and Liabilities which Provided (Used) Cash Exclusive of Changes Shown Separately
Accounts Receivable				(42,542)	(44,269)
Materials and Fuel Inventory				14,955	(32,448)
Accounts Payable				(8,678)	4,977
Income Taxes				(10,681)	(11,424)
Interest Accrued				1,008	2,729
Taxes Other Than Income Taxes				17,405	16,710
Other				15,234	11,898
Net Cash Provided by (Used in) Operating Activities				$ 254,179	$ 207,151