Condensed Consolidated Statements of Changes in Equity - USD ($)	Total	Total PNMR Common Stockholders’ Equity	Common Stock	AOCI	Retained Earnings	Non- controlling Interest in Valencia	PNM	PNM Total PNMR Common Stockholders’ Equity	PNM Common Stock	PNM AOCI	PNM Retained Earnings	PNM Non- controlling Interest in Valencia	Texas-New Mexico Power Company	Texas-New Mexico Power Company Common Stock	Texas-New Mexico Power Company Paid-in Capital	Texas-New Mexico Power Company Retained Earnings
Beginning balance at Dec. 31, 2018	$ 1,752,594,000	$ 1,688,382,000	$ 1,153,113,000	$ (108,684,000)	$ 643,953,000	$ 64,212,000	$ 1,461,571,000	$ 1,397,359,000	$ 1,264,918,000	$ (110,422,000)	$ 242,863,000	$ 64,212,000
Beginning balance TNMP at Dec. 31, 2018													$ 674,093,000	$ 64,000	$ 534,166,000	$ 139,863,000
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net earnings before subsidiary preferred stock dividends	(50,622,000)	(56,950,000)			(56,950,000)	6,328,000	(61,340,000)	(67,668,000)			(67,668,000)	6,328,000
Net earnings							(67,668,000)						19,365,000			19,365,000
Total other comprehensive income	8,502,000	8,502,000		8,502,000			10,474,000	10,474,000		10,474,000
Subsidiary preferred stock dividends	(264,000)	(264,000)			(264,000)
Dividends declared on preferred stock							(264,000)	(264,000)			(264,000)
Dividends declared on common stock	(23,099,000)	(23,099,000)			(23,099,000)		0						(14,811,000)			(14,811,000)
Proceeds from stock option exercise	943,000	943,000	943,000
Awards of common stock	(9,892,000)	(9,892,000)	(9,892,000)
Stock based compensation expense	4,526,000	4,526,000	4,526,000
Valencia’s transactions with its owner	(7,948,000)					(7,948,000)	(7,948,000)					(7,948,000)
Ending balance at Jun. 30, 2019	1,674,740,000	1,612,148,000	1,148,690,000	(100,182,000)	563,640,000	62,592,000	1,402,493,000	1,339,901,000	1,264,918,000	(99,948,000)	174,931,000	62,592,000
Ending balance TNMP at Jun. 30, 2019													678,647,000	64,000	534,166,000	144,417,000
Beginning balance at Mar. 31, 2019	1,747,458,000	1,684,679,000	1,148,364,000	(103,239,000)	639,554,000	62,779,000	1,485,307,000	1,422,528,000	1,264,918,000	(104,265,000)	261,875,000	62,779,000
Beginning balance TNMP at Mar. 31, 2019													667,478,000	64,000	534,166,000	133,248,000
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net earnings before subsidiary preferred stock dividends	(72,283,000)	(75,782,000)			(75,782,000)	3,499,000	(83,313,000)	(86,812,000)			(86,812,000)	3,499,000
Net earnings							(86,812,000)						15,267,000			15,267,000
Total other comprehensive income	3,057,000	3,057,000		3,057,000			4,317,000	4,317,000		4,317,000
Subsidiary preferred stock dividends	(132,000)
Dividends declared on preferred stock							(132,000)	(132,000)			(132,000)
Dividends declared on common stock	(132,000)	(132,000)			(132,000)		0						(4,098,000)			(4,098,000)
Proceeds from stock option exercise	13,000	13,000	13,000
Awards of common stock	(956,000)	(956,000)	(956,000)
Stock based compensation expense	1,269,000	1,269,000	1,269,000
Valencia’s transactions with its owner	(3,686,000)					(3,686,000)	(3,686,000)					(3,686,000)
Ending balance at Jun. 30, 2019	1,674,740,000	1,612,148,000	1,148,690,000	(100,182,000)	563,640,000	62,592,000	1,402,493,000	1,339,901,000	1,264,918,000	(99,948,000)	174,931,000	62,592,000
Ending balance TNMP at Jun. 30, 2019													678,647,000	64,000	534,166,000	144,417,000
Beginning balance at Dec. 31, 2019	1,741,750,000	1,678,698,000	1,150,552,000	(99,377,000)	627,523,000	63,052,000	1,512,431,000	1,449,379,000	1,264,918,000	(99,055,000)	283,516,000	63,052,000
Beginning balance TNMP at Dec. 31, 2019	1,678,698,000						1,449,379,000						754,627,000	64,000	614,166,000	140,397,000
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net earnings before subsidiary preferred stock dividends	50,162,000	42,493,000			42,493,000	7,669,000	37,416,000	29,747,000			29,747,000	7,669,000
Net earnings							29,747,000						23,266,000			23,266,000
Total other comprehensive income	6,796,000	6,796,000		6,796,000			8,063,000	8,063,000		8,063,000
Subsidiary preferred stock dividends	(264,000)	(264,000)			(264,000)
Dividends declared on preferred stock							(264,000)	(264,000)			(264,000)
Dividends declared on common stock	(24,493,000)	(24,493,000)			(24,493,000)		(40,654,000)	(40,654,000)			(40,654,000)		(18,439,000)			(18,439,000)
Proceeds from stock option exercise	24,000	24,000	24,000
Awards of common stock	(11,984,000)	(11,984,000)	(11,984,000)
Stock based compensation expense	5,230,000	5,230,000	5,230,000
Valencia’s transactions with its owner	(10,794,000)					(10,794,000)	(10,794,000)					(10,794,000)
Ending balance at Jun. 30, 2020	1,756,427,000	1,696,500,000	1,143,822,000	(92,581,000)	645,259,000	59,927,000	1,506,198,000	1,446,271,000	1,264,918,000	(90,992,000)	272,345,000	59,927,000
Ending balance TNMP at Jun. 30, 2020	1,696,500,000						1,446,271,000						759,454,000	64,000	614,166,000	145,224,000
Beginning balance at Mar. 31, 2020	1,687,569,000	1,627,222,000	1,142,879,000	(103,427,000)	587,770,000	60,347,000	1,450,484,000	1,390,137,000	1,264,918,000	(101,586,000)	226,805,000	60,347,000
Beginning balance TNMP at Mar. 31, 2020													750,372,000	64,000	614,166,000	136,142,000
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net earnings before subsidiary preferred stock dividends	61,561,000	57,621,000			57,621,000	3,940,000	49,612,000	45,672,000			45,672,000	3,940,000
Net earnings							45,672,000						16,174,000			16,174,000
Total other comprehensive income	10,846,000	10,846,000		10,846,000			10,594,000	10,594,000		10,594,000
Subsidiary preferred stock dividends	(132,000)	(132,000)			(132,000)
Dividends declared on preferred stock							(132,000)	(132,000)			(132,000)
Dividends declared on common stock							(40,700,000)						(7,092,000)			(7,092,000)
Awards of common stock	(486,000)	(486,000)	(486,000)
Stock based compensation expense	1,429,000	1,429,000	1,429,000
Valencia’s transactions with its owner	(4,360,000)					(4,360,000)	(4,360,000)					(4,360,000)
Ending balance at Jun. 30, 2020	1,756,427,000	$ 1,696,500,000	$ 1,143,822,000	$ (92,581,000)	$ 645,259,000	$ 59,927,000	1,506,198,000	$ 1,446,271,000	$ 1,264,918,000	$ (90,992,000)	$ 272,345,000	$ 59,927,000
Ending balance TNMP at Jun. 30, 2020	$ 1,696,500,000						$ 1,446,271,000						$ 759,454,000	$ 64,000	$ 614,166,000	$ 145,224,000