Pension and Other Postretirement Benefits APBO, PBO, Fair Value of Plan Assets, and Funded Status of the Plans (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Non-current liability	$ 80,046	$ 224,565
Public Service Company of New Mexico [Member]
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Non-current liability	76,611	208,618
Public Service Company of New Mexico [Member] | Pension Plan [Member]
Defined Benefit Plan, Change in Benefit Obligation [Roll Forward]
Benefit Obligation at beginning of year	675,549	588,874
Service cost	0	0	0
Interest cost	28,142	32,232	32,804
Actuarial (gain) loss	(56,533)	94,361
Benefits paid	(41,275)	(39,918)
Plan amendments	6,346	0
Benefit Obligation at end of year	599,537	675,549	588,874
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Fair value of plan assets at beginning of year	518,095	427,386
Actual return on plan assets	19,533	52,927
Employer contributions	60,000	77,700
Benefits paid	(41,275)	(39,918)
Fair value of plan assets at end of year	556,353	518,095	427,386
Funded status - asset (liability)	(43,184)	(157,454)
Public Service Company of New Mexico [Member] | Other Postretirement Benefits [Member]
Defined Benefit Plan, Change in Benefit Obligation [Roll Forward]
Benefit Obligation at beginning of year	99,613	96,221
Service cost	260	217	259
Interest cost	4,113	5,293	5,378
Participants contributions	2,537	2,266
Actuarial (gain) loss	(4,566)	5,008
Benefits paid	(9,792)	(9,392)
Benefit Obligation at end of year	92,165	99,613	96,221
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Fair value of plan assets at beginning of year	64,464	58,776
Actual return on plan assets	12,780	9,285
Employer contributions	3,576	3,529
Participants contributions	2,537	2,266
Benefits paid	(9,792)	(9,392)
Fair value of plan assets at end of year	73,565	64,464	58,776
Funded status - asset (liability)	(18,600)	(35,149)
Public Service Company of New Mexico [Member] | Executive Retirement Program [Member]
Defined Benefit Plan, Change in Benefit Obligation [Roll Forward]
Benefit Obligation at beginning of year	17,467	16,191
Service cost	0	0	0
Interest cost	720	876	930
Actuarial (gain) loss	(330)	1,895
Benefits paid	(1,494)	(1,495)
Benefit Obligation at end of year	16,363	17,467	16,191
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Benefits paid	(1,494)	(1,495)
Less current liability	1,536	1,452
Non-current liability	14,827	16,015
Texas-New Mexico Power Company [Member]
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Non-current liability	3,435	15,947
Texas-New Mexico Power Company [Member] | Pension Plan [Member]
Defined Benefit Plan, Change in Benefit Obligation [Roll Forward]
Benefit Obligation at beginning of year	76,640	67,234
Service cost	0	0	0
Interest cost	3,087	3,635	3,800
Actuarial (gain) loss	(7,820)	11,434
Benefits paid	(5,748)	(5,663)
Plan amendments	0	0
Benefit Obligation at end of year	66,159	76,640	67,234
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Fair value of plan assets at beginning of year	66,540	59,952
Actual return on plan assets	4,326	6,951
Employer contributions	1,000	5,300
Benefits paid	(5,748)	(5,663)
Fair value of plan assets at end of year	66,118	66,540	59,952
Funded status - asset (liability)	(41)	(10,100)
Texas-New Mexico Power Company [Member] | Other Postretirement Benefits [Member]
Defined Benefit Plan, Change in Benefit Obligation [Roll Forward]
Benefit Obligation at beginning of year	13,678	11,344
Service cost	299	244	306
Interest cost	566	624	654
Participants contributions	373	404
Actuarial (gain) loss	(1,080)	2,727
Benefits paid	(1,570)	(1,665)
Benefit Obligation at end of year	12,266	13,678	11,344
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Fair value of plan assets at beginning of year	8,643	8,303
Actual return on plan assets	1,813	1,259
Employer contributions	342	342
Participants contributions	373	404
Benefits paid	(1,570)	(1,665)
Fair value of plan assets at end of year	9,601	8,643	8,303
Funded status - asset (liability)	(2,665)	(5,035)
Texas-New Mexico Power Company [Member] | Executive Retirement Program [Member]
Defined Benefit Plan, Change in Benefit Obligation [Roll Forward]
Benefit Obligation at beginning of year	902	844
Service cost	0	0	0
Interest cost	36	45	46
Actuarial (gain) loss	(21)	107
Benefits paid	(94)	(94)
Benefit Obligation at end of year	823	902	844
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Benefits paid	(94)	(94)
Less current liability	94	90
Non-current liability	$ 729	$ 812