SUPPLEMENTAL CASH FLOW INFORMATION (Reconciliation of Net Income to Net Cash Flows from Operating Activities) (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2014	Mar. 31, 2013
Supplemental Cash Flow Information [Line Items]
Net Income	$ 15,475	$ 11,345
Adjustments to Reconcile Net Income To Net Cash Flows from Operating Activities
Depreciation Expense	39,081	36,300
Amortization Expense	6,176	8,289
Depreciation and Amortization Recorded to Fuel and Operations and Maintenance Expense	1,990	1,759
Amortization of Deferred Debt-Related Costs Included in Interest Expense	785	750
Provision for Retail Customer Bad Debts	537	318
Use of RECs for Compliance	5,528	3,870
Deferred Income Taxes	10,131	22,078
Pension and Postretirement Expense	3,942	5,696
Pension and Postretirement Funding	(1,694)	(1,734)
Share-Based Compensation Expense	985	722
Allowance for Equity Funds Used During Construction	(1,898)	(1,175)
Increase (Decrease) to Reflect PPFAC/PGA Recovery Treatment	(8,920)	(5,368)
Changes in Assets and Liabilities which Provided (Used) Cash Exclusive of Changes Shown Separately
Accounts Receivable	27,778	19,003
Materials and Fuel Inventory	(3,057)	1,574
Accounts Payable	(12,387)	(13,458)
Income Taxes	(146)	(16,028)
Interest Accrued	(6,426)	(9,974)
Taxes Other Than Income Taxes	11,697	12,534
Other	(12,792)	4,552
Net Cash Flows—Operating Activities	76,785	81,053
TUCSON ELECTRIC POWER COMPANY
Supplemental Cash Flow Information [Line Items]
Net Income	9,172	1,478
Adjustments to Reconcile Net Income To Net Cash Flows from Operating Activities
Depreciation Expense	30,811	28,558
Amortization Expense	7,099	9,222
Depreciation and Amortization Recorded to Fuel and Operations and Maintenance Expense	1,704	1,493
Amortization of Deferred Debt-Related Costs Included in Interest Expense	635	601
Provision for Retail Customer Bad Debts	342	246
Use of RECs for Compliance	4,844	3,540
Deferred Income Taxes	5,635	12,276
Pension and Postretirement Expense	3,412	4,970
Pension and Postretirement Funding	(1,657)	(1,676)
Share-Based Compensation Expense	792	575
Allowance for Equity Funds Used During Construction	(1,721)	(850)
Increase (Decrease) to Reflect PPFAC/PGA Recovery Treatment	(1,730)	(2,360)
Changes in Assets and Liabilities which Provided (Used) Cash Exclusive of Changes Shown Separately
Accounts Receivable	16,274	11,408
Materials and Fuel Inventory	(3,182)	1,654
Accounts Payable	(3,425)	(6,094)
Income Taxes	(5)	(10,877)
Interest Accrued	(3,260)	(6,826)
Taxes Other Than Income Taxes	9,948	10,068
Other	(10,374)	1,993
Net Cash Flows—Operating Activities	$ 65,314	$ 59,399