Consolidated Statements of Cash Flows - USD ($)	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Cash Flows From Operating Activities:
Net Earnings	$ 131,896,000	$ 31,078,000	$ 130,909,000
Net Earnings	116,849,000	15,640,000	116,254,000
Adjustments to reconcile net earnings to net cash flows from operating activities:
Depreciation and amortization	242,033,000	222,861,000	209,867,000
Net unrealized (gains) losses on commodity derivatives	1,577,000	5,188,000	(6,504,000)
Realized (gains) on available-for-sale securities	(19,517,000)	(16,060,000)	(10,527,000)
Stock based compensation expense	5,634,000	4,863,000	5,931,000
Regulatory disallowances and restructuring costs	15,011,000	167,471,000	1,062,000
Deferred income tax expense	63,805,000	16,451,000	72,481,000
Allowance for equity funds used during construction	(4,949,000)	(10,430,000)	(5,563,000)
Other, net	3,060,000	3,934,000	4,045,000
Changes in certain assets and liabilities:
Accounts receivable and unbilled revenues	2,543,000	(3,298,000)	(4,975,000)
Materials, supplies, and fuel stock	(4,169,000)	(180,000)	5,504,000
Other current assets	(2,469,000)	29,370,000	(30,436,000)
Other assets	(42,864,000)	2,369,000	290,000
Accounts payable	3,159,000	(32,269,000)	(2,311,000)
Accrued interest and taxes	3,345,000	4,957,000	2,040,000
Other current liabilities	(12,509,000)	2,633,000	(2,453,000)
Other liabilities	29,868,000	(42,064,000)	45,516,000
Net cash flows from operating activities	415,454,000	386,874,000	414,876,000
Cash Flows From Investing Activities:
Additions to utility and non-utility plant	(600,076,000)	(558,589,000)	(460,658,000)
Proceeds from sales of available-for-sale securities	522,601,000	252,174,000	117,989,000
Purchases of available-for-sale securities	(538,383,000)	(262,548,000)	(127,016,000)
Return of principal on PVNGS lessor notes	8,547,000	21,694,000	20,758,000
Purchase of Rio Bravo	0	0	(36,235,000)
Investment in Westmoreland Loan	(122,250,000)	0	0
Principal repayments on Westmoreland Loan	30,000,000	0	0
Other, net	186,000	2,741,000	(167,000)
Net cash flows from investing activities	(699,375,000)	(544,528,000)	(485,329,000)
Cash Flows From Financing Activities:
Short-term loan	100,000,000	50,000,000	0
Repayment of short-term loan	(150,000,000)	0	0
Revolving credit facilities borrowings (repayments), net	86,500,000	95,000,000	(43,600,000)
Long-term borrowings	603,500,000	463,605,000	355,000,000
Repayment of long-term debt	(303,793,000)	(333,066,000)	(125,000,000)
Proceeds from stock option exercise	7,028,000	5,619,000	6,999,000
Awards of common stock	(15,451,000)	(17,720,000)	(17,319,000)
Dividends paid	(70,623,000)	(64,251,000)	(59,468,000)
Valencia’s transactions with its owner	(17,006,000)	(17,049,000)	(17,610,000)
Other, net	2,237,000	(6,707,000)	(2,808,000)
Net cash flows from financing activities	242,392,000	175,431,000	96,194,000
Change in Cash and Cash Equivalents	(41,529,000)	17,777,000	25,741,000
Cash and Cash Equivalents at Beginning of Period	46,051,000	28,274,000	2,533,000
Cash and Cash Equivalents at End of Period	4,522,000	46,051,000	28,274,000
Supplemental Cash Flow Disclosures:
Interest paid, net of amounts capitalized	115,043,000	103,382,000	108,741,000
Income taxes paid (refunded), net	(307,000)	(1,890,000)	(2,597,000)
Supplemental schedule of noncash investing and financing activities:
(Increase) decrease in accrued plant additions	18,345,000	(19,080,000)	(3,089,000)
Public Service Company of New Mexico [Member]
Cash Flows From Operating Activities:
Net Earnings	91,938,000	(324,000)	101,453,000
Net Earnings	77,419,000	(15,234,000)	87,326,000
Adjustments to reconcile net earnings to net cash flows from operating activities:
Depreciation and amortization	166,047,000	150,538,000	143,303,000
Net unrealized (gains) losses on commodity derivatives	1,577,000	5,188,000	(6,504,000)
Realized (gains) on available-for-sale securities	(19,517,000)	(16,060,000)	(10,527,000)
Regulatory disallowances and restructuring costs	15,011,000	167,471,000	1,062,000
Deferred income tax expense	53,119,000	(2,836,000)	55,787,000
Allowance for equity funds used during construction	(4,163,000)	(10,430,000)	(5,563,000)
Other, net	3,046,000	2,794,000	4,172,000
Changes in certain assets and liabilities:
Accounts receivable and unbilled revenues	4,769,000	(2,515,000)	(5,919,000)
Materials, supplies, and fuel stock	(3,924,000)	381,000	5,570,000
Other current assets	1,127,000	23,693,000	(29,146,000)
Other assets	(23,880,000)	4,194,000	7,150,000
Accounts payable	5,614,000	(31,139,000)	212,000
Accrued interest and taxes	(9,601,000)	(5,343,000)	(3,599,000)
Other current liabilities	(12,136,000)	(275,000)	(659,000)
Other liabilities	20,119,000	(33,503,000)	42,325,000
Net cash flows from operating activities	289,146,000	251,834,000	299,117,000
Cash Flows From Investing Activities:
Additions to utility and non-utility plant	(445,464,000)	(404,840,000)	(316,800,000)
Proceeds from sales of available-for-sale securities	522,601,000	252,174,000	117,989,000
Purchases of available-for-sale securities	(538,383,000)	(262,548,000)	(127,016,000)
Return of principal on PVNGS lessor notes	8,547,000	21,694,000	20,758,000
Purchase of Rio Bravo	0	0	(36,235,000)
Other, net	171,000	2,935,000	(363,000)
Net cash flows from investing activities	(452,528,000)	(390,585,000)	(341,667,000)
Cash Flows From Financing Activities:
Revolving credit facilities borrowings (repayments), net	61,000,000	0	(49,200,000)
Short-term borrowings (repayments) - affiliate, net	0	0	(32,500,000)
Long-term borrowings	321,000,000	313,605,000	275,000,000
Repayment of long-term debt	(271,000,000)	(214,300,000)	(75,000,000)
Equity contribution from parent	28,142,000	175,000,000	0
Dividends paid	(4,670,000)	(94,968,000)	(30,791,000)
Valencia’s transactions with its owner	(17,006,000)	(17,049,000)	(17,610,000)
Other, net	3,102,000	(5,879,000)	(1,890,000)
Net cash flows from financing activities	120,568,000	156,409,000	68,009,000
Change in Cash and Cash Equivalents	(42,814,000)	17,658,000	25,459,000
Cash and Cash Equivalents at Beginning of Period	43,138,000	25,480,000	21,000
Cash and Cash Equivalents at End of Period	324,000	43,138,000	25,480,000
Supplemental Cash Flow Disclosures:
Interest paid, net of amounts capitalized	82,514,000	69,936,000	73,787,000
Income taxes paid (refunded), net	(967,000)	(1,450,000)	(228,000)
Supplemental schedule of noncash investing and financing activities:
(Increase) decrease in accrued plant additions	22,433,000	(17,469,000)	(1,616,000)
Texas-New Mexico Power Company [Member]
Cash Flows From Operating Activities:
Net Earnings	41,672,000	41,963,000	37,807,000
Adjustments to reconcile net earnings to net cash flows from operating activities:
Depreciation and amortization	62,866,000	57,909,000	52,847,000
Deferred income tax expense	12,662,000	20,883,000	20,549,000
Allowance for equity funds used during construction	(800,000)	0	0
Allowance for equity funds used during construction and other, net	(772,000)	18,000	(10,000)
Changes in certain assets and liabilities:
Accounts receivable and unbilled revenues	(2,226,000)	(783,000)	944,000
Materials, supplies, and fuel stock	(245,000)	(561,000)	(66,000)
Other current assets	(621,000)	3,928,000	380,000
Other assets	(19,126,000)	(2,310,000)	(6,607,000)
Accounts payable	(2,040,000)	(1,782,000)	2,514,000
Accrued interest and taxes	12,690,000	4,317,000	4,796,000
Other current liabilities	298,000	1,019,000	(203,000)
Other liabilities	6,822,000	(9,823,000)	3,112,000
Net cash flows from operating activities	111,980,000	114,778,000	116,063,000
Cash Flows From Investing Activities:
Additions to utility and non-utility plant	(122,518,000)	(124,584,000)	(127,191,000)
Net cash flows from investing activities	(122,518,000)	(124,584,000)	(127,191,000)
Cash Flows From Financing Activities:
Revolving credit facilities borrowings (repayments), net	(59,000,000)	54,000,000	5,000,000
Short-term borrowings (repayments) - affiliate, net	(7,200,000)	(10,900,000)	(6,700,000)
Long-term borrowings	60,000,000	0	80,000,000
Repayment of long-term debt	0	0	(50,000,000)
Equity contribution from parent	50,000,000	0	0
Dividends paid	(31,817,000)	(33,248,000)	(16,336,000)
Other, net	(775,000)	(46,000)	(836,000)
Net cash flows from financing activities	11,208,000	9,806,000	11,128,000
Change in Cash and Cash Equivalents	670,000	0	0
Cash and Cash Equivalents at Beginning of Period	1,000	1,000	1,000
Cash and Cash Equivalents at End of Period	671,000	1,000	1,000
Supplemental Cash Flow Disclosures:
Interest paid, net of amounts capitalized	26,766,000	26,216,000	22,803,000
Income taxes paid (refunded), net	660,000	290,000	(355,000)
Supplemental schedule of noncash investing and financing activities:
(Increase) decrease in accrued plant additions	$ (1,271,000)	$ (5,000)	$ 854,000