Quarterly Operating Results (Unaudited) (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Segment Reporting Information [Line Items]
Operating revenues	$ 335,894	$ 417,433	$ 352,887	$ 332,868	$ 346,845	$ 413,951	$ 346,160	$ 328,897	$ 1,439,082	$ 1,435,853	$ 1,387,923
Operating income	(119,138)	121,505	72,414	49,569	62,849	116,799	71,296	48,753	124,350	299,697	286,842
Net earnings	(87,284)	64,855	35,655	17,852	22,111	59,486	33,181	16,131	31,078	130,909	115,556
Earnings Attributable to PNMR	$ (91,418)	$ 61,045	$ 31,673	$ 14,340	$ 18,992	$ 55,653	$ 29,141	$ 12,468	$ 15,640	$ 116,254	$ 100,507
Net Earnings Attributable to PNMR per Common Share:
Basic (dollars per share)	$ (1.15)	$ 0.77	$ 0.40	$ 0.18	$ 0.24	$ 0.70	$ 0.37	$ 0.16	$ 0.20	$ 1.46	$ 1.26
Diluted (dollars per share)	$ (1.15)	$ 0.76	$ 0.40	$ 0.18	$ 0.24	$ 0.69	$ 0.36	$ 0.16	$ 0.20	$ 1.45	$ 1.25
Regulatory disallowances and restructuring costs									$ 167,471	$ 1,062	$ 12,235
Public Service Company of New Mexico [Member]
Segment Reporting Information [Line Items]
Operating revenues	$ 260,368	$ 333,437	$ 275,450	$ 261,940	$ 274,481	$ 334,993	$ 275,704	$ 262,736	1,131,195	1,147,914	1,116,312
Operating income	(139,164)	93,710	47,179	31,655	40,988	90,615	49,806	31,304	33,380	212,713	209,185
Net earnings	(92,245)	53,056	25,363	13,502	16,942	49,052	24,254	11,205	(324)	101,453	102,676
Earnings Attributable to PNMR	(96,247)	49,378	21,513	10,122	13,955	45,351	20,346	7,674	(15,234)	87,326	88,155
Net Earnings Attributable to PNMR per Common Share:
Regulatory disallowances and restructuring costs									167,471	1,062	12,235
Public Service Company of New Mexico [Member] | Clean Air Act, SNCR [Member]
Net Earnings Attributable to PNMR per Common Share:
Regulatory disallowances and restructuring costs									21,600
Public Service Company of New Mexico [Member] | Clean Air Act, SNCR [Member] | San Juan Generating Station Units 2 and 3 [Member]
Net Earnings Attributable to PNMR per Common Share:
Regulatory disallowances and restructuring costs									127,600
Public Service Company of New Mexico [Member] | Increase in coal mine decommissioning liability [Member] | Clean Air Act, SNCR [Member] | San Juan Generating Station Units 2 and 3 [Member]
Net Earnings Attributable to PNMR per Common Share:
Regulatory disallowances and restructuring costs									165,700
Texas-New Mexico Power Company [Member]
Segment Reporting Information [Line Items]
Operating revenues									307,887	287,939	271,611
Operating income	19,706	27,667	24,729	17,931	21,188	25,873	21,265	17,262	90,033	85,588	72,185
Earnings Attributable to PNMR	8,715	13,689	11,865	7,694	9,115	12,355	9,534	6,803	$ 41,963	$ 37,807	$ 29,090
Operating revenues	$ 75,526	$ 83,996	$ 77,437	$ 70,928	$ 72,364	$ 78,958	$ 70,456	$ 66,161