Earnings Per Share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Earnings Per Share [Abstract]
Net Earnings Attributable to PNMR	$ 15,991	$ 17,579
Average Number of Common Shares:
Outstanding during period (in shares)	85,835	85,835
Vested awards of restricted stock (in shares)	256	196
Average Shares – Basic (in shares)	86,091	86,031
Dilutive Effect of Common Stock Equivalents:
Restricted stock (in shares)	80	24
Average Shares – Diluted (in shares)	86,171	86,055
Net Earnings Per Share of Common Stock:
Basic (in dollars per share)	$ 0.19	$ 0.20
Diluted (in dollars per share)	$ 0.19	$ 0.20