Construction Program and Jointly-Owned Electric Generating Plants Construction Program and Jointly-Owned Electric Generating Plants (Details) (USD $)	12 Months Ended
	Dec. 31, 2013		Dec. 31, 2012	Dec. 31, 2011
Construction Expenditures	$ 348,039,000		$ 308,909,000	$ 326,931,000
Public Utilities, Property, Plant and Equipment, Plant in Service	5,563,061,000		5,313,796,000
Public Utilities, Property, Plant and Equipment, Accumulated Depreciation	(1,838,832,000)		(1,774,223,000)
Operating Lease, Extended Term	2 years
Public Service Company of New Mexico [Member]
Construction Expenditures	239,906,000		196,800,000	251,345,000
Public Utilities, Property, Plant and Equipment, Plant in Service	4,314,016,000		4,133,532,000
Public Utilities, Property, Plant and Equipment, Accumulated Depreciation	(1,402,531,000)		(1,355,240,000)
Texas-New Mexico Power Company [Member]
Construction Expenditures	89,117,000		92,973,000	67,407,000
Public Utilities, Property, Plant and Equipment, Plant in Service	1,074,193,000		1,009,108,000
Public Utilities, Property, Plant and Equipment, Accumulated Depreciation	(352,105,000)		(339,315,000)
Joint Projects [Member] | Public Service Company of New Mexico [Member]
Construction Expenditures	239,900,000
Joint Projects [Member] | Texas-New Mexico Power Company [Member]
Construction Expenditures	89,100,000
Joint Projects [Member] | PNMR [Member]
Construction Expenditures	348,000,000
Four Corners Units 4 and 5 (Coal) [Member] | Public Service Company of New Mexico [Member]
Public Utilities, Property, Plant and Equipment, Plant in Service	159,016,000
Public Utilities, Property, Plant and Equipment, Accumulated Depreciation	(100,462,000)
Public Utilities, Property, Plant and Equipment, Construction Work in Progress	3,236,000
Jointly Owned Utility Plant, Proportionate Ownership Share	13.00%
Environmental Upgrades Requirement Estimates	80,300,000
Luna (Gas) [Member] | Other Unrelated Entities 9 [Member]
Jointly Owned Utility Plant, Proportionate Ownership Share	33.30%
Luna (Gas) [Member] | Public Service Company of New Mexico [Member]
Public Utilities, Property, Plant and Equipment, Plant in Service	62,873,000
Public Utilities, Property, Plant and Equipment, Accumulated Depreciation	(17,743,000)
Public Utilities, Property, Plant and Equipment, Construction Work in Progress	169,000
Jointly Owned Utility Plant, Proportionate Ownership Share	33.33%
SJGS Units 1 and 2 [Member] | Public Service Company of New Mexico [Member]
Jointly Owned Utility Plant, Proportionate Ownership Share	50.00%
SJGS (Coal) [Member] | Unit 3 [Member] | Other Unrelated Entities 1 [Member]
Jointly Owned Utility Plant Proportionate Ownership Share, Other Entities	41.80%
SJGS (Coal) [Member] | Unit 3 [Member] | Other Unrelated Entities 2 [Member]
Jointly Owned Utility Plant, Proportionate Ownership Share	8.20%
SJGS (Coal) [Member] | Unit 4 [Member] | Other Unrelated Entities 3 [Member]
Jointly Owned Utility Plant Proportionate Ownership Share, Other Entities	28.80%
SJGS (Coal) [Member] | Unit 4 [Member] | Other Unrelated Entities 4 [Member]
Jointly Owned Utility Plant Proportionate Ownership Share, Other Entities	10.04%
SJGS (Coal) [Member] | Unit 4 [Member] | Other Unrelated Entities 5 [Member]
Jointly Owned Utility Plant Proportionate Ownership Share, Other Entities	8.475%
SJGS (Coal) [Member] | Unit 4 [Member] | Other Unrelated Entities 6 [Member]
Jointly Owned Utility Plant Proportionate Ownership Share, Other Entities	7.20%
SJGS (Coal) [Member] | Unit 4 [Member] | Other Unrelated Entities 7 [Member]
Jointly Owned Utility Plant Proportionate Ownership Share, Other Entities	7.028%
SJGS (Coal) [Member] | Public Service Company of New Mexico [Member]
Public Utilities, Property, Plant and Equipment, Plant in Service	1,004,138,000
Public Utilities, Property, Plant and Equipment, Accumulated Depreciation	(414,054,000)
Public Utilities, Property, Plant and Equipment, Construction Work in Progress	13,860,000
Jointly Owned Utility Plant, Proportionate Ownership Share	46.30%
SJGS (Coal) [Member] | Public Service Company of New Mexico [Member] | Unit 3 [Member]
Jointly Owned Utility Plant, Proportionate Ownership Share	50.00%
SJGS (Coal) [Member] | Public Service Company of New Mexico [Member] | Unit 4 [Member]
Jointly Owned Utility Plant, Proportionate Ownership Share	38.457%
Palo Verde Nuclear Generating Station [Member] | Public Service Company of New Mexico [Member]
Public Utilities, Property, Plant and Equipment, Plant in Service	508,426,000	[1]
Public Utilities, Property, Plant and Equipment, Accumulated Depreciation	(141,347,000)	[1]
Public Utilities, Property, Plant and Equipment, Construction Work in Progress	$ 43,627,000	[1]
Jointly Owned Utility Plant, Proportionate Ownership Share	10.20%	[1]
Operating Lease, Original term	40 years
Number of operating units	3
Operating Lease, Extended Term	20 years

[1] Includes interest in PVNGS Unit 3, interest in common facilities for all PVNGS units, and owned interests in PVNGS Units 1 and 2.