Regulatory Assets and Liabilities (Details) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012
Regulatory Assets
Regulatory Assets, Current	$ 24,416	$ 39,120
Regulatory Assets, Noncurrent	523,955	555,577
Regulatory Liabilities
Regulatory Liability, Current	(1,081)	(15,173)
Regulatory liabilities, Noncurrent	(460,649)	(423,460)
Public Service Company of New Mexico [Member]
Regulatory Assets
Regulatory Assets, Current	19,394	36,490
Regulatory Assets, Noncurrent	384,217	431,956
Regulatory Assets	403,611	468,446
Regulatory Liabilities
Regulatory Liability, Current	(1,081)	(15,172)
Regulatory liabilities, Noncurrent	(414,611)	(379,841)
Regulatory Liabilities	(415,692)	(395,013)
Texas-New Mexico Power Company [Member]
Regulatory Assets
Regulatory Assets, Current	5,022	2,630
Regulatory Assets, Noncurrent	139,738	123,621
Regulatory Assets	144,760	126,251
Regulatory Liabilities
Regulatory liabilities, Noncurrent	(46,038)	(43,619)
Deferred income taxes Member] | Public Service Company of New Mexico [Member]
Regulatory Liabilities
Regulatory liabilities, Noncurrent	(80,495)	(49,723)
Deferred income taxes Member] | Texas-New Mexico Power Company [Member]
Regulatory Liabilities
Regulatory liabilities, Noncurrent	(4,563)	(5,203)
Advanced Metering Infrastructure Costs [Member] | Texas-New Mexico Power Company [Member]
Regulatory Liabilities
Regulatory liabilities, Noncurrent	7,251	6,386
Other [Member] | Public Service Company of New Mexico [Member]
Regulatory Liabilities
Regulatory Liability, Current	(1,081)	(15,172)
Removal Costs [Member] | Public Service Company of New Mexico [Member]
Regulatory Liabilities
Regulatory liabilities, Noncurrent	(266,075)	(257,396)
Removal Costs [Member] | Texas-New Mexico Power Company [Member]
Regulatory Liabilities
Regulatory liabilities, Noncurrent	(30,863)	(31,115)
Asset retirement obligations [Member] | Public Service Company of New Mexico [Member]
Regulatory Liabilities
Regulatory liabilities, Noncurrent	(37,567)	(39,280)
Renewable energy costs [Member] | Public Service Company of New Mexico [Member]
Regulatory Liabilities
Regulatory liabilities, Noncurrent	(26,011)	(26,988)
Other [Member] | Public Service Company of New Mexico [Member]
Regulatory Liabilities
Regulatory liabilities, Noncurrent	(4,463)	(6,454)
Other [Member] | Texas-New Mexico Power Company [Member]
Regulatory Liabilities
Regulatory liabilities, Noncurrent	(3,361)	(915)
Regulatory Assets, Transmission Cost Recovery | Texas-New Mexico Power Company [Member]
Regulatory Assets
Regulatory Assets, Current	4,250	2,287
Regulatory Assets, Other Current [Member] | Public Service Company of New Mexico [Member]
Regulatory Assets
Regulatory Assets, Current	0	224
Stranded costs [Member] | Texas-New Mexico Power Company [Member]
Regulatory Assets
Regulatory Assets, Noncurrent	63,606	71,240
Environmental Restoration Costs [Member] | Public Service Company of New Mexico [Member]
Regulatory Assets
Regulatory Assets, Noncurrent	40,144	46,065
Deferred income taxes Member] | Public Service Company of New Mexico [Member]
Regulatory Assets
Regulatory Assets, Noncurrent	61,850	54,781
Deferred income taxes Member] | Texas-New Mexico Power Company [Member]
Regulatory Assets
Regulatory Assets, Noncurrent	10,868	11,179
Pension and Other Postretirement Plans Costs [Member] | Public Service Company of New Mexico [Member]
Regulatory Assets
Regulatory Assets, Noncurrent	206,691	254,351
Pension and Other Postretirement Plans Costs [Member] | Texas-New Mexico Power Company [Member]
Regulatory Assets
Regulatory Assets, Noncurrent	19,938	28,307
Loss on reacquired debt [Member] | Public Service Company of New Mexico [Member]
Regulatory Assets
Regulatory Assets, Noncurrent	27,490	29,702
Loss on reacquired debt [Member] | Texas-New Mexico Power Company [Member]
Regulatory Assets
Regulatory Assets, Noncurrent	38,616	1,711
Fuel and purchased power adjustment clause [Member]
Regulatory Assets
Regulatory Assets, Current	49,100
Fuel and purchased power adjustment clause [Member] | Public Service Company of New Mexico [Member]
Regulatory Assets
Regulatory Assets, Current	19,394	36,266
Regulatory Assets, Noncurrent	25,386	18,619
Renewable energy costs [Member] | Public Service Company of New Mexico [Member]
Regulatory Assets
Regulatory Assets, Noncurrent	13,311	18,768
Hurricane recovery costs [Member] | Texas-New Mexico Power Company [Member]
Regulatory Assets
Regulatory Assets, Noncurrent	0	4,572
Advanced Metering Infrastructure Costs [Member] | Texas-New Mexico Power Company [Member]
Regulatory Assets
Regulatory Assets, Noncurrent	5,083	3,538
Other [Member] | Public Service Company of New Mexico [Member]
Regulatory Assets
Regulatory Assets, Noncurrent	9,345	9,670
Other [Member] | Texas-New Mexico Power Company [Member]
Regulatory Assets
Regulatory Assets, Current	772	343
Regulatory Assets, Noncurrent	$ 1,627	$ 3,074