Pension and Other Postretirement Benefits Pre-Tax Information about Prior Service Cost and Net Actuarial (Gain) loss in AOCI (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2013
Public Service Company of New Mexico [Member] | Pension Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Prior service cost (credit) - Amounts in AOCI not yet recognized in net periodic benefit cost (income) at beginning of year	$ 32
Net actuarial (gain) loss - Amounts in AOCI not yet recognized in net periodic benefit cost (income) at beginning of year	159,826
Prior service cost (credit) - Experience loss (gain)	0
Net actuarial (gain) loss - Experience loss (gain)	(34,136)
Prior service cost (credit) - Regulatory asset (liability) adjustment	0
Net actuarial (gain) loss - Regulatory asset (liability) adjustment	19,799
Other Comprehensive Income (Loss), Pension and Other Postretirement Benefit Plans, Prior Service Costs, Plan Amendments, before Tax	(2,665)
Other Comprehensive Income (Loss), Pension and Other Postretirement Benefit Plans, Net Actuarial (Gain) Loss, Plan Amendments, before Tax	0
Prior service cost (credit) - Amortization recognized in net periodic benefit cost (income)	(32)
Net actuarial (gain) loss - Amortization recognized in net periodic benefit cost (income)	(6,233)
Prior service cost (credit) - Amounts in AOCI not yet recognized in net periodic benefit cost (income) at end of year	(2,665)
Net actuarial (gain) loss - Amounts in AOCI not yet recognized in net periodic benefit cost (income) at end of year	139,256
Prior service cost (credit) - Amortization expected to be recognized in in 2013	(405)
Net actuarial (gain) loss - Amortization expected to be recognized in in 2013	5,469
Public Service Company of New Mexico [Member] | Other Postretirement Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Net actuarial (gain) loss - Experience loss (gain)	(12,300)
Public Service Company of New Mexico [Member] | Executive Retirement Program [Member]
Defined Benefit Plan Disclosure [Line Items]
Net actuarial (gain) loss - Amounts in AOCI not yet recognized in net periodic benefit cost (income) at beginning of year	2,069
Net actuarial (gain) loss - Experience loss (gain)	(330)
Net actuarial (gain) loss - Regulatory asset (liability) adjustment	192
Net actuarial (gain) loss - Amortization recognized in net periodic benefit cost (income)	(98)
Net actuarial (gain) loss - Amounts in AOCI not yet recognized in net periodic benefit cost (income) at end of year	1,833
Net actuarial (gain) loss - Amortization expected to be recognized in in 2013	88
Texas-New Mexico Power Company [Member] | Pension Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Net actuarial (gain) loss - Amounts in AOCI not yet recognized in net periodic benefit cost (income) at beginning of year	0
Net actuarial (gain) loss - Experience loss (gain)	(7,297)
Net actuarial (gain) loss - Regulatory asset (liability) adjustment	7,297
Other Comprehensive Income (Loss), Pension and Other Postretirement Benefit Plans, Net Actuarial (Gain) Loss, Plan Amendments, before Tax	0
Net actuarial (gain) loss - Amortization recognized in net periodic benefit cost (income)	0
Net actuarial (gain) loss - Amounts in AOCI not yet recognized in net periodic benefit cost (income) at end of year	0
Net actuarial (gain) loss - Amortization expected to be recognized in in 2013	0
Texas-New Mexico Power Company [Member] | Other Postretirement Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Net actuarial (gain) loss - Experience loss (gain)	(2,400)
Texas-New Mexico Power Company [Member] | Executive Retirement Program [Member]
Defined Benefit Plan Disclosure [Line Items]
Net actuarial (gain) loss - Amounts in AOCI not yet recognized in net periodic benefit cost (income) at beginning of year	0
Net actuarial (gain) loss - Experience loss (gain)	(22)
Net actuarial (gain) loss - Regulatory asset (liability) adjustment	22
Net actuarial (gain) loss - Amortization recognized in net periodic benefit cost (income)	0
Net actuarial (gain) loss - Amounts in AOCI not yet recognized in net periodic benefit cost (income) at end of year	0
Net actuarial (gain) loss - Amortization expected to be recognized in in 2013	$ 0