Fair Value of Derivative and Other Financial Instruments - Commodity Derivatives (Details) - USD ($)	Dec. 31, 2016	Dec. 31, 2015
Derivatives, Fair Value [Line Items]
Current assets	$ 5,224,000	$ 3,813,000
Deferred charges	0	2,622,000
Current liabilities	(2,339,000)	(1,859,000)
PNMR and PNM [Member]
Derivatives, Fair Value [Line Items]
Amounts recognized for the legal right to reclaim cash collateral	0	0
Amounts posted as cash collateral under margin arrangements	2,600,000	2,700,000
Obligations to return cash collateral	100,000	100,000
PNMR and PNM [Member] | Designated as hedging instrument [Member] | Commodity Contract [Member]
Derivatives, Fair Value [Line Items]
Current assets	5,224,000	3,813,000
Deferred charges	0	2,622,000
Total assets	5,224,000	6,435,000
Current liabilities	(2,339,000)	(1,859,000)
Net	2,885,000	4,576,000
PNMR and PNM [Member] | Designated as hedging instrument [Member] | Commodity Contract [Member] | Palo Verde Nuclear Generating Station [Member]
Derivatives, Fair Value [Line Items]
Current assets	2,700,000	3,000,000
Deferred charges		2,600,000
Public Service Company of New Mexico [Member]
Derivatives, Fair Value [Line Items]
Current assets	5,224,000	3,813,000
Deferred charges	0	2,622,000
Current liabilities	(2,339,000)	(1,859,000)
Public Service Company of New Mexico [Member] | Designated as hedging instrument [Member] | Commodity Contract [Member] | Fuel and Purchased Power Adjustment Clause [Member]
Derivatives, Fair Value [Line Items]
Current assets	200,000	400,000
Current liabilities	$ (100,000)	$ (200,000)