Earnings and Dividends Per Share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Earnings Per Share [Abstract]
Net Earnings Attributable to PNMR	$ 87,818	$ 169,530	$ 195,829
Average Number of Common Shares:
Outstanding during year (in shares)	86,038	85,835	85,835
Vested awards of restricted stock (in shares)	258	287	235
Average Shares – Basic (in shares)	86,296	86,122	86,070
Dilutive Effect of Common Stock Equivalents:
PNMR 2020 Forward Equity Sale Agreements (in shares)	38	0	0
Stock options and restricted stock (in shares)	35	47	41
Average Shares – Diluted (in shares)	86,369	86,169	86,111
Net Earnings Attributable to PNMR Per Share of Common Stock:
Basic (in dollars per share)	$ 1.02	$ 1.97	$ 2.28
Diluted (in dollars per share)	1.02	1.97	2.27
Dividends Declared per Common Share (in dollars per share)	$ 1.49	$ 1.41	$ 1.33