Consolidated Statements of Cash Flows - USD ($)	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Cash Flows From Operating Activities:
Net Earnings	$ 187,316,000	$ 92,131,000	$ 101,282,000
Adjustments to reconcile net earnings to net cash flows from operating activities:
Depreciation and amortization	314,668,000	301,068,000	275,641,000
Deferred income tax expense (benefit)	20,405,000	(25,385,000)	8,019,000
(Gains) losses on investment securities	(21,599,000)	(29,589,000)	17,176,000
Stock based compensation expense	8,141,000	6,414,000	7,120,000
Regulatory disallowances and restructuring costs	1,098,000	151,095,000	65,598,000
Allowance for equity funds used during construction	(11,254,000)	(9,478,000)	(10,404,000)
Other, net	3,497,000	2,395,000	3,529,000
Changes in certain assets and liabilities:
Accounts receivable and unbilled revenues	(42,035,000)	3,796,000	(8,702,000)
Materials, supplies, and fuel stock	11,512,000	(6,095,000)	(5,331,000)
Other current assets	(8,135,000)	1,872,000	2,491,000
Other assets	29,923,000	42,803,000	(840,000)
Accounts payable	7,403,000	(272,000)	(20,714,000)
Accrued interest and taxes	(9,347,000)	14,691,000	1,713,000
Other current liabilities	23,740,000	(7,212,000)	2,614,000
Other liabilities	(29,633,000)	(35,071,000)	(10,966,000)
Net cash flows from operating activities	485,700,000	503,163,000	428,226,000
Cash Flows From Investing Activities:
Additions to utility and non-utility plant	(679,028,000)	(616,273,000)	(501,213,000)
Proceeds from sales of investment securities	590,998,000	494,528,000	984,533,000
Purchases of investment securities	(607,591,000)	(513,866,000)	(1,007,022,000)
Investments in NMRD	(23,250,000)	(38,250,000)	(9,000,000)
Principal repayments on Westmoreland Loan	0	0	56,640,000
Other, net	(14,928,000)	(37,000)	338,000
Net cash flows from investing activities	(733,799,000)	(673,898,000)	(475,724,000)
Cash Flows From Financing Activities:
Short-term loan borrowings (repayments)	0	(150,000,000)	50,000,000
Revolving credit facilities borrowings (repayments), net	(153,100,000)	99,200,000	(119,500,000)
Long-term borrowings	1,267,845,000	745,000,000	984,652,000
Repayment of long-term debt	(977,845,000)	(407,302,000)	(750,162,000)
Issuance of common stock	283,208,000	0	0
Proceeds from stock option exercise	24,000	943,000	963,000
Awards of common stock	(11,984,000)	(9,918,000)	(12,635,000)
Dividends paid	(98,502,000)	(92,926,000)	(84,961,000)
Valencia’s transactions with its owner	(18,056,000)	(15,401,000)	(17,095,000)
Amounts received under transmission interconnection arrangements	11,452,000	10,015,000	4,060,000
Refunds paid under transmission interconnection arrangements	(5,905,000)	(4,325,000)	(2,830,000)
Other, net	(4,943,000)	(2,840,000)	(6,846,000)
Net cash flows from financing activities	292,194,000	172,446,000	45,646,000
Change in Cash and Cash Equivalents	44,095,000	1,711,000	(1,852,000)
Cash and Cash Equivalents at Beginning of Year	3,833,000	2,122,000	3,974,000
Cash and Cash Equivalents at End of Year	47,928,000	3,833,000	2,122,000
Supplemental Cash Flow Disclosures:
Interest paid, net of amounts capitalized	106,575,000	115,476,000	119,308,000
Income taxes paid (refunded), net	969,000	(2,929,000)	842,000
Supplemental schedule of noncash investing and financing activities:
(Increase) decrease in accrued plant additions	(58,796,000)	8,781,000	(11,502,000)
Contribution of utility plant to NMRD	801,000	0	578,000
Public Service Company of New Mexico
Cash Flows From Operating Activities:
Net Earnings	160,014,000	55,422,000	70,323,000
Net earnings	146,001,000	41,181,000	55,211,000
Adjustments to reconcile net earnings to net cash flows from operating activities:
Depreciation and amortization	198,418,000	191,213,000	182,355,000
Deferred income tax expense (benefit)	22,442,000	(20,145,000)	3,334,000
(Gains) losses on investment securities	(21,599,000)	(29,589,000)	17,176,000
Regulatory disallowances and restructuring costs	1,098,000	150,599,000	66,339,000
Allowance for equity funds used during construction	(6,958,000)	(6,656,000)	(8,173,000)
Other, net	4,950,000	2,697,000	3,395,000
Changes in certain assets and liabilities:
Accounts receivable and unbilled revenues	(41,340,000)	5,877,000	(7,959,000)
Materials, supplies, and fuel stock	11,753,000	(5,128,000)	(6,238,000)
Other current assets	(2,718,000)	(1,453,000)	(468,000)
Other assets	24,882,000	31,409,000	6,894,000
Accounts payable	6,267,000	(3,617,000)	(14,290,000)
Accrued interest and taxes	(11,572,000)	5,579,000	(7,617,000)
Other current liabilities	16,682,000	18,002,000	(17,975,000)
Other liabilities	(36,556,000)	(39,087,000)	(3,761,000)
Net cash flows from operating activities	325,763,000	355,123,000	283,335,000
Cash Flows From Investing Activities:
Additions to utility and non-utility plant	(335,055,000)	(341,847,000)	(255,627,000)
Proceeds from sales of investment securities	590,998,000	494,528,000	984,533,000
Purchases of investment securities	(607,591,000)	(513,866,000)	(1,007,022,000)
Other, net	(14,942,000)	(87,000)	544,000
Net cash flows from investing activities	(366,590,000)	(361,272,000)	(277,572,000)
Cash Flows From Financing Activities:
Short-term loan borrowings (repayments)	(48,000,000)	15,600,000	2,600,000
Short-term borrowings (repayments) - affiliate, net	0	(19,800,000)	19,800,000
Long-term borrowings	852,845,000	290,000,000	450,000,000
Repayment of long-term debt	(902,845,000)	(200,000,000)	(450,025,000)
Equity contribution from parent	230,000,000	0	0
Dividends paid	(41,181,000)	(528,000)	(77,904,000)
Valencia’s transactions with its owner	(18,056,000)	(15,401,000)	(17,095,000)
Amounts received under transmission interconnection arrangements	4,050,000	10,015,000	72,260,000
Refunds paid under transmission interconnection arrangements	(5,905,000)	(72,525,000)	(2,830,000)
Other, net	364,000	(296,000)	(3,592,000)
Net cash flows from financing activities	71,272,000	7,065,000	(6,786,000)
Change in Cash and Cash Equivalents	30,445,000	916,000	(1,023,000)
Cash and Cash Equivalents at Beginning of Year	1,001,000	85,000	1,108,000
Cash and Cash Equivalents at End of Year	31,446,000	1,001,000	85,000
Supplemental Cash Flow Disclosures:
Interest paid, net of amounts capitalized	60,663,000	65,445,000	73,029,000
Income taxes paid (refunded), net	0	(3,544,000)	134,000
Supplemental schedule of noncash investing and financing activities:
(Increase) decrease in accrued plant additions	(48,037,000)	4,751,000	(12,310,000)
Texas-New Mexico Power Company
Cash Flows From Operating Activities:
Net earnings	58,585,000	55,799,000	51,591,000
Adjustments to reconcile net earnings to net cash flows from operating activities:
Depreciation and amortization	89,010,000	85,453,000	68,078,000
Deferred income tax expense (benefit)	(7,773,000)	(7,650,000)	1,780,000
Regulatory disallowances and restructuring costs	0	496,000	(741,000)
Allowance for equity funds used during construction	(4,300,000)	(2,800,000)	(2,200,000)
Allowance for equity funds used during construction and other, net	(4,305,000)	(2,808,000)	(2,048,000)
Other, net
Changes in certain assets and liabilities:
Accounts receivable and unbilled revenues	(695,000)	(2,081,000)	(744,000)
Materials, supplies, and fuel stock	(241,000)	(967,000)	907,000
Other current assets	(1,291,000)	(798,000)	1,929,000
Other assets	8,553,000	8,366,000	(7,174,000)
Accounts payable	1,607,000	1,829,000	(4,199,000)
Accrued interest and taxes	(530,000)	186,000	12,263,000
Other current liabilities	2,518,000	771,000	6,719,000
Other liabilities	2,135,000	(1,004,000)	(6,610,000)
Net cash flows from operating activities	147,573,000	137,592,000	121,751,000
Cash Flows From Investing Activities:
Additions to utility and non-utility plant	(321,505,000)	(254,006,000)	(223,448,000)
Net cash flows from investing activities	(321,505,000)	(254,006,000)	(223,448,000)
Cash Flows From Financing Activities:
Short-term loan borrowings (repayments)	(15,000,000)	(2,500,000)	17,500,000
Short-term borrowings (repayments) - affiliate, net	0	(100,000)	100,000
Long-term borrowings	185,000,000	305,000,000	95,000,000
Repayment of long-term debt	0	(207,302,000)	0
Equity contribution from parent	71,000,000	80,000,000	30,000,000
Dividends paid	(58,534,000)	(55,265,000)	(41,903,000)
Amounts received under transmission interconnection arrangements	7,402,000	0	0
Other, net	(2,136,000)	(2,419,000)	(700,000)
Net cash flows from financing activities	187,732,000	117,414,000	99,997,000
Change in Cash and Cash Equivalents	13,800,000	1,000,000	(1,700,000)
Cash and Cash Equivalents at Beginning of Year	1,000,000	0	1,700,000
Cash and Cash Equivalents at End of Year	14,800,000	1,000,000	0
Supplemental Cash Flow Disclosures:
Interest paid, net of amounts capitalized	28,114,000	28,055,000	28,629,000
Income taxes paid (refunded), net	16,790,000	13,611,000	4,266,000
Supplemental schedule of noncash investing and financing activities:
(Increase) decrease in accrued plant additions	$ (11,415,000)	$ 5,035,000	$ 1,810,000