DEBT, CREDIT FACILITIES, AND CAPITAL LEASE OBLIGATIONS (Debt) (Detail) (USD $)	3 Months Ended
Mar. 31, 2014	Mar. 31, 2013
Debt Instrument [Line Items]
Repayment of outstanding credit facility	$ 114,000,000	$ 35,000,000
TUCSON ELECTRIC POWER COMPANY
Debt Instrument [Line Items]
Repayment of outstanding credit facility	105,000,000	35,000,000
TUCSON ELECTRIC POWER COMPANY \| Unsecured Debt [Member]
Debt Instrument [Line Items]
Debt instrument, face amount	150,000,000	91,000,000
Fixed interest rate of long-term debt	5.00%
Revolving Credit Facility [Member] \| TUCSON ELECTRIC POWER COMPANY
Debt Instrument [Line Items]
Repayment of outstanding credit facility	$ 90,000,000

Amount of cash outflow for payment of an obligation from a lender, including but not limited to, letter of credit, standby letter of credit and revolving credit arrangements.

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 235

-SubTopic 10

-Section S99

-Paragraph 1

-Subparagraph (SX 210.4-08.(f))

-URI http://asc.fasb.org/extlink&oid=26873400&loc=d3e23780-122690

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 08

-Paragraph f

-Article 4

Reference 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 230

-SubTopic 10

-Section 45

-Paragraph 15

-Subparagraph (b)

-URI http://asc.fasb.org/extlink&oid=31042434&loc=d3e3291-108585

Reference 4: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Glossary Financing Activities

-URI http://asc.fasb.org/extlink&oid=6513228

Name:	us-gaap_RepaymentsOfLinesOfCredit
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration