Schedule I - Condensed Financial Information of Parent Company - Statement of Cash flow (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Condensed Financial Statements, Captions [Line Items]
Net Cash Flows From Operating Activities	$ 415,454	$ 386,874	$ 414,876
Cash Flows From Investing Activities:
Net cash flows from investing activities	(699,375)	(544,528)	(485,329)
Cash Flows From Financing Activities:
Short-term loan	100,000	50,000	0
Repayment of short-term loan	(150,000)	0	0
Short-term borrowings (repayments), net	86,500	95,000	(43,600)
Long-term borrowings	603,500	463,605	355,000
Repayment of long-term debt	(303,793)	(333,066)	(125,000)
Proceeds from stock option exercise	7,028	5,619	6,999
Dividends paid	(70,623)	(64,251)	(59,468)
Other, net	2,237	(6,707)	(2,808)
Net cash flows from financing activities	242,392	175,431	96,194
Change in Cash and Cash Equivalents	(41,529)	17,777	25,741
Cash and Cash Equivalents at Beginning of Period	46,051	28,274	2,533
Cash and Cash Equivalents at End of Period	4,522	46,051	28,274
Supplemental Cash Flow Disclosures:
Interest paid, net of amounts capitalized	115,043	103,382	108,741
Income taxes paid (refunded), net	(307)	(1,890)	(2,597)
PNM Resources [Member]
Condensed Financial Statements, Captions [Line Items]
Net Cash Flows From Operating Activities	5,702	1,375	22,744
Cash Flows From Investing Activities:
Utility plant additions	341	368	(474)
Investments in subsidiaries	(98,343)	(175,000)	0
Cash dividends from subsidiaries	35,959	127,688	46,599
Net cash flows from investing activities	(62,043)	(46,944)	46,125
Cash Flows From Financing Activities:
Short-term loan	100,000	50,000	0
Repayment of short-term loan	(150,000)	0	0
Short-term borrowings (repayments), net	84,500	41,000	600
Long-term borrowings	100,000	150,000
Repayment of long-term debt	0	(118,766)	0
Proceeds from stock option exercise	7,028	5,619	6,999
Purchases to satisfy awards of common stock	(15,451)	(17,720)	(17,319)
Dividends paid	(70,095)	(63,723)	(58,940)
Other, net	(28)	(782)	81
Net cash flows from financing activities	55,954	45,628	(68,579)
Change in Cash and Cash Equivalents	(387)	59	290
Cash and Cash Equivalents at Beginning of Period	441	382	92
Cash and Cash Equivalents at End of Period	54	441	382
Supplemental Cash Flow Disclosures:
Interest paid, net of amounts capitalized	5,906	7,559	12,152
Income taxes paid (refunded), net	$ 0	$ (730)	$ (2,014)