Financing Schedule of Long-term Debt (Details) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Apr. 03, 2013	Mar. 06, 2013
Debt Instrument [Line Items]
Long-term Debt	$ 1,975,090us-gaap_LongTermDebt	$ 1,745,420us-gaap_LongTermDebt
Less current maturities	333,066us-gaap_LongTermDebtCurrent	75,000us-gaap_LongTermDebtCurrent
Long-term Debt, Excluding Current Maturities	1,642,024us-gaap_LongTermDebtNoncurrent	1,670,420us-gaap_LongTermDebtNoncurrent
Unsecured Debt [Member]
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Stated Percentage		9.25%
Unsecured Debt [Member] \| Senior unsecured notes, 9.25% due 2015 [Member]
Debt Instrument [Line Items]
Unsecured Long-term Debt, Noncurrent	118,766	118,766
Public Service Company of New Mexico [Member]
Debt Instrument [Line Items]
Long-term Debt	1,490,657	1,290,618
Less current maturities	214,300	75,000
Long-term Debt, Excluding Current Maturities	1,276,357	1,215,618
Public Service Company of New Mexico [Member] \| Senior Unsecured Notes, Pollution Control Revenue Bonds [Member] \| 4.875% due 2033 [Member]
Debt Instrument [Line Items]
Unsecured Long-term Debt, Noncurrent	146,000	146,000
Debt Instrument, Interest Rate, Stated Percentage	4.875%	4.875%
Public Service Company of New Mexico [Member] \| Senior Unsecured Notes, Pollution Control Revenue Bonds [Member] \| 6.25% due 2038 [Member]
Debt Instrument [Line Items]
Unsecured Long-term Debt, Noncurrent	36,000	36,000
Debt Instrument, Interest Rate, Stated Percentage	6.25%	6.25%
Public Service Company of New Mexico [Member] \| Senior Unsecured Notes, Pollution Control Revenue Bonds [Member] \| 4.75% due 2040, mandatory tender at June 1, 2017 [Member]
Debt Instrument [Line Items]
Unsecured Long-term Debt, Noncurrent	37,000	37,000
Debt Instrument, Interest Rate, Stated Percentage	4.75%	4.75%
Public Service Company of New Mexico [Member] \| Senior Unsecured Notes, Pollution Control Revenue Bonds [Member] \| 5.20% due 2040, mandatory tender at June 1, 2020 [Member]
Debt Instrument [Line Items]
Unsecured Long-term Debt, Noncurrent	40,045	40,045
Debt Instrument, Interest Rate, Stated Percentage	5.20%	5.20%
Public Service Company of New Mexico [Member] \| Senior Unsecured Notes, Pollution Control Revenue Bonds [Member] \| 5.90% due 2040 [Member]
Debt Instrument [Line Items]
Unsecured Long-term Debt, Noncurrent	255,000	255,000
Debt Instrument, Interest Rate, Stated Percentage	5.90%	5.90%
Public Service Company of New Mexico [Member] \| Senior Unsecured Notes, Pollution Control Revenue Bonds [Member] \| 6.25% due 2040 [Member]
Debt Instrument [Line Items]
Unsecured Long-term Debt, Noncurrent	11,500	11,500
Debt Instrument, Interest Rate, Stated Percentage	6.25%	6.25%
Public Service Company of New Mexico [Member] \| Senior Unsecured Notes, Pollution Control Revenue Bonds [Member] \| 2.54% due 2042, mandatory tender at June 1, 2017 [Member]
Debt Instrument [Line Items]
Unsecured Long-term Debt, Noncurrent	20,000	20,000
Debt Instrument, Interest Rate, Stated Percentage	2.54%	2.54%
Public Service Company of New Mexico [Member] \| Senior Unsecured Notes, Pollution Control Revenue Bonds [Member] \| 4.00% due 2043, mandatory tender at June 1, 2015 [Member]
Debt Instrument [Line Items]
Unsecured Long-term Debt, Noncurrent	39,300	39,300
Debt Instrument, Interest Rate, Stated Percentage	4.00%	4.00%
Public Service Company of New Mexico [Member] \| Senior Unsecured Notes, Pollution Control Revenue Bonds [Member] \| 5.20% due 2043, mandatory tender at June 1, 2020 [Member]
Debt Instrument [Line Items]
Unsecured Long-term Debt, Noncurrent	21,000	21,000
Debt Instrument, Interest Rate, Stated Percentage	5.20%	5.20%
Public Service Company of New Mexico [Member] \| Unsecured Debt [Member] \| 7.95% due 2018 [Member]
Debt Instrument [Line Items]
Unsecured Long-term Debt, Noncurrent	350,000	350,000
Debt Instrument, Interest Rate, Stated Percentage	7.95%	7.95%
Public Service Company of New Mexico [Member] \| Unsecured Debt [Member] \| 7.50% due 2018 [Member]
Debt Instrument [Line Items]
Unsecured Long-term Debt, Noncurrent	100,025	100,025
Debt Instrument, Interest Rate, Stated Percentage	7.50%	7.50%
Public Service Company of New Mexico [Member] \| Unsecured Debt [Member] \| 5.35% due 2021 [Member]
Debt Instrument [Line Items]
Unsecured Long-term Debt, Noncurrent	160,000	160,000
Debt Instrument, Interest Rate, Stated Percentage	5.35%	5.35%
Public Service Company of New Mexico [Member] \| Unsecured Debt [Member] \| PNM 2014 Term Loan Agreement [Member]
Debt Instrument [Line Items]
Long-term Debt	0	75,000
Public Service Company of New Mexico [Member] \| Unsecured Debt [Member] \| PNM Term Loan Agreement due 2015 [Member]
Debt Instrument [Line Items]
Long-term Debt	175,000	0
Public Service Company of New Mexico [Member] \| Unsecured Debt [Member] \| PNM Multi-Draw Term Loan Agreement due 2016 [Member]
Debt Instrument [Line Items]
Long-term Debt	100,000	0
Public Service Company of New Mexico [Member] \| Other [Member]
Debt Instrument [Line Items]
Unamortized premiums (discounts)	(213)	(252)
Texas-New Mexico Power Company [Member]
Debt Instrument [Line Items]
Long-term Debt	365,667	336,036
Less current maturities	0	0
Long-term Debt, Excluding Current Maturities	365,667	336,036
Texas-New Mexico Power Company [Member] \| First Mortgage Bonds [Member] \| 2011 Term Loan Agreement, due 2014 [Member]
Debt Instrument [Line Items]
Long-term Debt	0	50,000
Texas-New Mexico Power Company [Member] \| First Mortgage Bonds [Member] \| First Mortgage Bonds Due 2014, Series 2009A, at 9 point 50 percent [Member]
Debt Instrument [Line Items]
Unsecured Long-term Debt, Noncurrent	172,302	172,302
Debt Instrument, Interest Rate, Stated Percentage	9.50%	9.50%	9.50%	9.50%
Texas-New Mexico Power Company [Member] \| First Mortgage Bonds [Member] \| First Mortgage Bonds 6 Point 95 Percent, due 2043, Series 2013A [Member]
Debt Instrument [Line Items]
Unsecured Long-term Debt, Noncurrent	93,198	93,198
Debt Instrument, Interest Rate, Stated Percentage	6.95%	6.95%	6.95%	6.95%
Texas-New Mexico Power Company [Member] \| First Mortgage Bonds [Member] \| First Mortgage Bonds Due 2024, Series 2014A, at 4 point 03 percent [Member] [Member]
Debt Instrument [Line Items]
Unsecured Long-term Debt, Noncurrent	80,000	0
Debt Instrument, Interest Rate, Stated Percentage	4.03%
Texas-New Mexico Power Company [Member] \| Other [Member]
Debt Instrument [Line Items]
Unamortized premiums (discounts)	(20,167)	(20,536)
PNMR [Member]
Debt Instrument [Line Items]
Less current maturities	118,766	0
Long-term Debt, Excluding Current Maturities	$ 0	$ 118,766
PNMR [Member] \| Unsecured Debt [Member] \| Senior unsecured notes, 9.25% due 2015 [Member]
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Stated Percentage	9.25%	9.25%