QUARTERLY FINANCIAL DATA - Summary of Quarterly Financial Data (Detail) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Quarterly Financial Information [Line Items]
Operating Revenue	$ 350,161	$ 437,041	$ 365,217	$ 332,141	$ 348,273	$ 434,108	$ 363,998	$ 315,387	$ 1,484,560	$ 1,461,766	$ 1,478,702
Operating Income	41,033	129,765	60,803	39,895	42,918	106,409	68,065	34,403	271,496	251,795	281,707
Net Income (Loss)	13,525	67,990	34,618	11,345	7,506	50,664	26,273	6,476	127,478	90,919	109,975
Basic EPS	$ 0.32	$ 1.63	$ 0.83	$ 0.27	$ 0.18	$ 1.22	$ 0.65	$ 0.17	$ 3.06	$ 2.25	$ 2.98
Diluted EPS	$ 0.32	$ 1.62	$ 0.83	$ 0.27	$ 0.18	$ 1.21	$ 0.64	$ 0.17	$ 3.04	$ 2.20	$ 2.75
TUCSON ELECTRIC POWER COMPANY
Quarterly Financial Information [Line Items]
Operating Revenue	273,437	371,239	304,263	247,751	271,353	366,910	299,419	223,978	1,196,690	1,161,660	1,156,386
Operating Income	31,014	123,177	53,433	22,747	30,299	94,079	58,211	17,898	230,371	200,487	229,408
Net Income (Loss)	$ 4,910	$ 64,167	$ 30,787	$ 1,478	$ 452	$ 44,569	$ 21,910	$ (1,461)	$ 101,342	$ 65,470	$ 85,334