Schedule I - Condensed Financial Information of Parent Company - Statement of Cash flow (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Cash Flows From Operating Activities:
Net Cash Flows From Operating Activities	$ 547,873	$ 485,700	$ 503,163
Cash Flows From Investing Activities:
Net cash flows used in investing activities	(952,258)	(733,799)	(673,898)
Cash Flows From Financing Activities:
Revolving credit facility borrowings (repayments), net	30,700	(153,100)	99,200
Long-term borrowings	1,816,345	1,267,845	745,000
Repayment of long-term debt	(1,411,345)	(977,845)	(407,302)
Issuance of common stock	0	283,208	0
Proceeds from stock option exercise	0	24	943
Dividends paid	(112,972)	(98,502)	(92,926)
Debt issuance costs and other, net	(6,306)	(4,943)	(2,840)
Net cash flows from financing activities	357,561	292,194	172,446
Change in Cash and Cash Equivalents	(46,824)	44,095	1,711
Cash and Cash Equivalents at Beginning of Year	47,928	3,833	2,122
Cash and Cash Equivalents at End of Year	1,104	47,928	3,833
Supplemental Cash Flow Disclosures:
Interest paid, net of amounts capitalized	91,276	106,575	115,476
Income taxes paid (refunded), net	1,042	969	(2,929)
PNM Resources
Cash Flows From Operating Activities:
Net Cash Flows From Operating Activities	(28,514)	(17,646)	2,001
Cash Flows From Investing Activities:
Utility plant additions	543	1,122	1,100
Investments in subsidiaries	(178,071)	(301,000)	(80,000)
Cash dividends from subsidiaries	60,000	99,187	54,465
Net cash flows used in investing activities	(117,528)	(200,691)	(24,435)
Cash Flows From Financing Activities:
Short-term borrowings (repayments), net	0	0	(150,000)
Short-term borrowings (repayments) -affiliate, net	6,400	0	0
Revolving credit facility borrowings (repayments), net	42,900	(131,900)	123,900
Long-term borrowings	1,120,000	230,000	150,000
Repayment of long-term debt	(900,000)	(50,000)	0
Issuance of common stock	0	283,208	0
Proceeds from stock option exercise	0	24	943
Awards of common stock	(10,130)	(11,984)	(9,918)
Dividends paid	(112,444)	(97,974)	(92,398)
Debt issuance costs and other, net	(673)	(3,064)	(107)
Net cash flows from financing activities	146,053	218,310	22,420
Change in Cash and Cash Equivalents	11	(27)	(14)
Cash and Cash Equivalents at Beginning of Year	52	79	93
Cash and Cash Equivalents at End of Year	63	52	79
Supplemental Cash Flow Disclosures:
Interest paid, net of amounts capitalized	13,425	16,869	18,702
Income taxes paid (refunded), net	$ 0	$ 0	$ 0