Schedule I - Condensed Financial Information of Parent Company (Statement of Cash flow) (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Cash Flows From Operating Activities:
Net Earnings	$ (91,418)	$ 61,045	$ 31,673	$ 14,340	$ 18,992	$ 55,653	$ 29,141	$ 12,468	$ 15,640	$ 116,254	$ 100,507
Adjustments to reconcile net earnings to net cash flows from operating activities:
Depreciation and amortization									222,861	209,867	208,173
Deferred income tax expense									16,451	72,481	60,430
Loss on reacquired debt									0	0	3,253
Stock based compensation expense									4,863	5,931	5,320
Changes in certain assets and liabilities:
Other current assets									29,370	(30,436)	8,577
Other assets									2,369	290	(12,801)
Accounts payable									(32,269)	(2,311)	4,484
Accrued interest and taxes									4,957	2,040	91,537
Other current liabilities									2,633	(2,453)	(19,648)
Other liabilities									(42,064)	45,516	(61,262)
Net cash flows from operating activities									386,874	414,876	386,587
Cash Flows From Investing Activities:
Utility plant additions									(558,589)	(460,658)	(348,039)
Net cash flows from investing activities									(544,528)	(485,329)	(331,446)
Cash Flows From Financing Activities:
Short-term loan									50,000	0	0
Short-term borrowings (repayments), net									95,000	(43,600)	(9,500)
Long-term borrowings									463,605	355,000	75,000
Repayment of long-term debt									(333,066)	(125,000)	(29,468)
Proceeds from stock option exercise									5,619	6,999	4,618
Dividends paid									(64,251)	(59,468)	(51,508)
Other, net									(6,707)	(2,808)	(5,545)
Net cash flows from financing activities									175,431	96,194	(61,593)
Change in Cash and Cash Equivalents									17,777	25,741	(6,452)
Cash and Cash Equivalents at Beginning of Year				28,274				2,533	28,274	2,533	8,985
Cash and Cash Equivalents at End of Year	46,051				28,274				46,051	28,274	2,533
Supplemental Cash Flow Disclosures:
Interest paid, net of amounts capitalized									103,382	108,741	110,768
Income taxes paid (refunded), net									(1,890)	(2,597)	(95,327)
PNM Resources [Member]
Cash Flows From Operating Activities:
Net Earnings									15,640	116,254	100,507
Adjustments to reconcile net earnings to net cash flows from operating activities:
Depreciation and amortization									509	680	4,192
Deferred income tax expense									(79,526)	(69,442)	(51,820)
Equity in (earnings) of subsidiaries									(27,352)	(124,543)	(116,634)
Loss on reacquired debt									0	0	3,253
Stock based compensation expense									4,863	5,931	5,320
Changes in certain assets and liabilities:
Other current assets									7,664	22,955	28,460
Other assets									69,443	51,644	46,558
Accounts payable									370	(88)	620
Accrued interest and taxes									4,823	(7,683)	(9,266)
Other current liabilities									0	(1,668)	(146)
Other liabilities									4,941	28,704	(27,756)
Net cash flows from operating activities									1,375	22,744	(16,712)
Cash Flows From Investing Activities:
Utility plant additions									368	(474)	(960)
Investments in subsidiaries									(175,000)	0	(13,800)
Cash dividends from subsidiaries									127,688	46,599	158,772
Net cash flows from investing activities									(46,944)	46,125	144,012
Cash Flows From Financing Activities:
Short-term loan									50,000	0	0
Short-term borrowings (repayments), net									41,000	600	(37,600)
Long-term borrowings									150,000
Repayment of long-term debt									(118,766)	0	(29,468)
Proceeds from stock option exercise									5,619	6,999	4,618
Purchases to satisfy awards of common stock									(17,720)	(17,319)	(13,807)
Dividends paid									(63,723)	(58,940)	(50,980)
Other, net									(782)	81	0
Net cash flows from financing activities									45,628	(68,579)	(127,237)
Change in Cash and Cash Equivalents									59	290	63
Cash and Cash Equivalents at Beginning of Year				$ 382				$ 92	382	92	29
Cash and Cash Equivalents at End of Year	$ 441				$ 382				441	382	92
Supplemental Cash Flow Disclosures:
Interest paid, net of amounts capitalized									7,559	12,152	14,510
Income taxes paid (refunded), net									$ (730)	$ (2,014)	$ 22,378