NATURE OF OPERATIONS AND FINANCIAL STATEMENT PRESENTATION (Additional Information) (Detail) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2014	Mar. 31, 2013
Document Fiscal Year Focus	2014	2013
Deferred Income Taxes Current And Noncurrent [Member]
Quantifying Misstatement in Current Year Financial Statements, Amount	$ 7
Deferred Income Taxes Current And Noncurrent [Member] | TUCSON ELECTRIC POWER COMPANY
Quantifying Misstatement in Current Year Financial Statements, Amount	7
Capital Lease Obligation Current And Noncurrent [Member]
Quantifying Misstatement in Current Year Financial Statements, Amount	18
Capital Lease Obligation Current And Noncurrent [Member] | TUCSON ELECTRIC POWER COMPANY
Quantifying Misstatement in Current Year Financial Statements, Amount	$ 18