Condensed Consolidated Statements of Changes in Equity - USD ($) $ in Thousands	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	$ 1,688,382	$ 1,153,113	$ (108,684)	$ 643,953	$ 64,212	$ 1,461,571	$ 1,397,359	$ 1,264,918	$ (110,422)	$ 242,863	$ 64,212
Beginning balance TNMP at Dec. 31, 2018													$ 674,093	$ 64	$ 534,166	$ 139,863
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net earnings (loss) before subsidiary preferred stock dividends	21,662	18,832			18,832	2,830	21,974	19,144			19,144	2,830
Net earnings							19,144						4,098			4,098
Total other comprehensive income (loss)	5,445	5,445		5,445			6,157	6,157		6,157
Subsidiary preferred stock dividends	(132)	(132)			(132)
Dividends declared on preferred stock							(132)	(132)			(132)
Dividends declared on common stock	(23,099)	(23,099)			(23,099)								(10,713)			(10,713)
Proceeds from stock option exercise	930	930	930
Awards of common stock	(8,936)	(8,936)	(8,936)
Stock based compensation expense	3,257	3,257	3,257
Valencia’s transactions with its owner	(4,263)					(4,263)	(4,263)					(4,263)
Ending balance at Mar. 31, 2019	1,747,458	1,684,679	1,148,364	(103,239)	639,554	62,779	1,485,307	1,422,528	1,264,918	(104,265)	261,875	62,779
Ending balance TNMP at Mar. 31, 2019													667,478	64	534,166	133,248
Beginning balance at Dec. 31, 2019	1,741,750	1,678,698	1,150,552	(99,377)	627,523	63,052	1,512,431	1,449,379	1,264,918	(99,055)	283,516	63,052
Beginning balance TNMP at Dec. 31, 2019	1,678,698						1,449,379						754,627	64	614,166	140,397
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net earnings (loss) before subsidiary preferred stock dividends	(11,399)	(15,128)			(15,128)	3,729	(12,196)	(15,925)			(15,925)	3,729
Net earnings							(15,925)						7,092			7,092
Total other comprehensive income (loss)	(4,050)	(4,050)		(4,050)			(2,531)	(2,531)		(2,531)
Subsidiary preferred stock dividends	(132)	(132)			(132)
Dividends declared on preferred stock							(132)	(132)			(132)
Dividends declared on common stock	(24,493)	(24,493)			(24,493)		(40,654)	(40,654)			(40,654)		(11,347)			(11,347)
Proceeds from stock option exercise	24	24	24
Awards of common stock	(11,498)	(11,498)	(11,498)
Stock based compensation expense	3,801	3,801	3,801
Valencia’s transactions with its owner	(6,434)					(6,434)	(6,434)					(6,434)
Ending balance at Mar. 31, 2020	1,687,569	$ 1,627,222	$ 1,142,879	$ (103,427)	$ 587,770	$ 60,347	1,450,484	$ 1,390,137	$ 1,264,918	$ (101,586)	$ 226,805	$ 60,347
Ending balance TNMP at Mar. 31, 2020	$ 1,627,222						$ 1,390,137						$ 750,372	$ 64	$ 614,166	$ 136,142