COMMITMENTS, CONTINGENCIES, AND ENVIRONMENTAL MATTERS (Commitments) (Details) (USD $) In Millions, unless otherwise specified	Dec. 31, 2013
Unrecorded Unconditional Purchase Obligation [Line Items]
2014	$ 234
2015	163
2016	141
2017	135
2018	108
Thereafter	956
Total	1,737
Fuel [Member]
Unrecorded Unconditional Purchase Obligation [Line Items]
2014	103
2015	83
2016	80
2017	75
2018	49
Thereafter	345
Total	735
Purchased Power [Member]
Unrecorded Unconditional Purchase Obligation [Line Items]
2014	75
2015	17
2016	0
2017	0
2018	0
Thereafter	0
Total	92
Transmission Facilities [Member]
Unrecorded Unconditional Purchase Obligation [Line Items]
2014	7
2015	13
2016	12
2017	12
2018	11
Thereafter	27
Total	82
Renewable Energy Power Purchase Agreement [Member]
Unrecorded Unconditional Purchase Obligation [Line Items]
2014	36
2015	37
2016	37
2017	37
2018	37
Thereafter	485
Total	669
RES Performance Based Incentives Minimum Commitment [Member]
Unrecorded Unconditional Purchase Obligation [Line Items]
2014	9
2015	9
2016	9
2017	9
2018	9
Thereafter	85
Total	130
Operating Lease [Member]
Unrecorded Unconditional Purchase Obligation [Line Items]
2014	4
2015	4
2016	3
2017	2
2018	2
Thereafter	14
Total	29
TUCSON ELECTRIC POWER COMPANY
Unrecorded Unconditional Purchase Obligation [Line Items]
2014	148
2015	116
2016	111
2017	109
2018	83
Thereafter	813
Total	1,380
TUCSON ELECTRIC POWER COMPANY | Fuel [Member]
Unrecorded Unconditional Purchase Obligation [Line Items]
2014	77
2015	63
2016	64
2017	62
2018	36
Thereafter	285
Total	587
TUCSON ELECTRIC POWER COMPANY | Purchased Power [Member]
Unrecorded Unconditional Purchase Obligation [Line Items]
2014	27
2015	5
2016	0
2017	0
2018	0
Thereafter	0
Total	32
TUCSON ELECTRIC POWER COMPANY | Transmission Facilities [Member]
Unrecorded Unconditional Purchase Obligation [Line Items]
2014	3
2015	6
2016	6
2017	6
2018	6
Thereafter	21
Total	48
TUCSON ELECTRIC POWER COMPANY | Renewable Energy Power Purchase Agreement [Member]
Unrecorded Unconditional Purchase Obligation [Line Items]
2014	30
2015	31
2016	31
2017	31
2018	31
Thereafter	410
Total	564
TUCSON ELECTRIC POWER COMPANY | RES Performance Based Incentives Minimum Commitment [Member]
Unrecorded Unconditional Purchase Obligation [Line Items]
2014	8
2015	8
2016	8
2017	8
2018	8
Thereafter	83
Total	123
TUCSON ELECTRIC POWER COMPANY | Operating Lease [Member]
Unrecorded Unconditional Purchase Obligation [Line Items]
2014	3
2015	3
2016	2
2017	2
2018	2
Thereafter	14
Total	$ 26