Stockholders' Equity (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Line of Credit [Member]
Class of Stock [Line Items]
Debt-to-capital ratio (not more than)	65.00%
Public Service Company of New Mexico [Member]
Class of Stock [Line Items]
Equity contribution from parent	$ 28,142	$ 175,000	$ 0
Preferred stock, dividend rate	4.58%
Preferred stock, redemption percent	102.00%
Preferred stock outstanding (in shares)	115,293	115,293
Preferred stock, cumulative shares authorized (in shares)	10,000,000	10,000,000
Public Service Company of New Mexico [Member] | Maximum [Member]
Class of Stock [Line Items]
Requirement to obtain approval to transfer more than a percentage of PNM's assets	5.00%
Public Service Company of New Mexico [Member] | Affiliated Entity [Member]
Class of Stock [Line Items]
Cash dividends paid to parent company by consolidated subsidiaries	$ 4,100	$ 94,400	30,300
Texas-New Mexico Power Company [Member]
Class of Stock [Line Items]
Equity contribution from parent	$ 50,000	0	0
Preferred stock, cumulative shares authorized (in shares)	1,000,000
Texas-New Mexico Power Company [Member] | Line of Credit [Member]
Class of Stock [Line Items]
Debt-to-capital ratio (not more than)	65.00%
Texas-New Mexico Power Company [Member] | Affiliated Entity [Member]
Class of Stock [Line Items]
Cash dividends paid to parent company by consolidated subsidiaries	$ 31,800	$ 33,200	$ 16,300
PNMR and TNMP [Member]
Class of Stock [Line Items]
Preferred stock outstanding (in shares)	0