Income Taxes Carryforwards (Details) - USD ($)	1 Months Ended	12 Months Ended
	May. 31, 2013	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Operating Loss Carryforwards [Line Items]
New Mexico corporate tax rate being phased in		7.60%
New Mexico Corporate tax rate, effective by 2018		5.90%
Decrease in regulatory liabilities due to change in state corporate tax rate		$ (1,903,000)	$ (5,106,000)
Decrease in income tax expense due to tax rate change		(674,000)	(71,000)
Increase in regulatory liabilities due to change in state corporate tax rate				$ 23,896,000
Increase in income tax expense due to change in state corporate tax rate				1,233,000
State tax credit carryforwards, impairments		3,092,000	894,000	3,880,000
State net operating loss carryforward, impairment		5,278,000	3,129,000
Charitable contribution carryforward, Impairment		2,042,000
State tax credit carryforwards, reserve balances		6,378,000	5,492,000
State net operating loss carryforwards, reserve balances		361,000	3,129,000
Charitable contribution carryforwards, reserve balances		659,000
Total refunds	$ 96,200,000
Liability (refund) adjustment from settlement with taxing authority			2,000,000
Income tax expense (benefit)		15,075,000	69,738,000	59,513,000
Adjustments for New Accounting Pronouncement [Member]
Operating Loss Carryforwards [Line Items]
Amounts reclassified		26,400,000
Corporate and Other [Member]
Operating Loss Carryforwards [Line Items]
Income tax expense (benefit)		3,708,000	(5,418,000)	(6,912,000)
Internal Revenue Service (IRS) [Member]
Operating Loss Carryforwards [Line Items]
Federal net operating loss carryforwards		427,400,000
Federal tax credit carryforwards that expire beginning in 2023		77,400,000
Income tax expense (benefit)			(200,000)
Internal Revenue Service (IRS) [Member] | Corporate and Other [Member]
Operating Loss Carryforwards [Line Items]
Income tax expense (benefit)			(1,300,000)
Public Service Company of New Mexico [Member]
Operating Loss Carryforwards [Line Items]
Decrease in regulatory liabilities due to change in state corporate tax rate		(1,903,000)	(5,106,000)
Decrease in income tax expense due to tax rate change		(470,000)	(312,000)
Increase in regulatory liabilities due to change in state corporate tax rate				23,896,000
Increase in income tax expense due to change in state corporate tax rate				0
State tax credit carryforwards, impairments		0	0	0
State net operating loss carryforward, impairment		3,619,000	2,145,000
Charitable contribution carryforward, Impairment		0
State tax credit carryforwards, reserve balances		0	0
State net operating loss carryforwards, reserve balances		248,000	2,145,000
Charitable contribution carryforwards, reserve balances		0
Total refunds	$ 77,400,000
Income tax expense (benefit)		(12,758,000)	52,633,000	48,804,000
Public Service Company of New Mexico [Member] | Adjustments for New Accounting Pronouncement [Member]
Operating Loss Carryforwards [Line Items]
Amounts reclassified		12,400,000
Public Service Company of New Mexico [Member] | Internal Revenue Service (IRS) [Member]
Operating Loss Carryforwards [Line Items]
Income tax expense (benefit)			1,100,000
Texas-New Mexico Power Company [Member]
Operating Loss Carryforwards [Line Items]
Decrease in regulatory liabilities due to change in state corporate tax rate		0	0
Decrease in income tax expense due to tax rate change		0	0
Increase in regulatory liabilities due to change in state corporate tax rate				0
Increase in income tax expense due to change in state corporate tax rate				0
State tax credit carryforwards, impairments		0	0	0
State net operating loss carryforward, impairment		0	0
Charitable contribution carryforward, Impairment		0
State tax credit carryforwards, reserve balances		0	0
State net operating loss carryforwards, reserve balances		0	0
Charitable contribution carryforwards, reserve balances		0
Income tax expense (benefit)		24,125,000	22,523,000	$ 17,621,000
Texas-New Mexico Power Company [Member] | Adjustments for New Accounting Pronouncement [Member]
Operating Loss Carryforwards [Line Items]
Amounts reclassified		$ 6,400,000
Texas-New Mexico Power Company [Member] | Internal Revenue Service (IRS) [Member]
Operating Loss Carryforwards [Line Items]
Income tax expense (benefit)			$ 0