Segment Information (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012	Dec. 31, 2012
Segment Reporting Information, Profit (Loss) [Abstract]
Electric operating revenues	$ 347,599	$ 323,860	$ 665,263	$ 629,234
Cost of energy	105,659	94,719	210,365	186,565
Margin	241,940	229,141	454,898	442,669
Other operating expenses	122,434	122,981	243,881	244,366
Depreciation and amortization	41,639	41,054	82,446	79,468
Operating income	77,867	65,106	128,571	118,835
Interest income	2,833	3,386	5,467	6,678
Other income (deductions)	1,633	(1,649)	1,524	899
Net interest charges	(30,616)	(30,198)	(61,914)	(59,765)
Earnings before Income Taxes	51,717	36,645	73,648	66,647
Income taxes (benefit)	20,334	11,546	28,303	21,071
Net Earnings	31,383	25,099	45,345	45,576
Valencia non-controlling interest	(3,573)	(3,455)	(6,777)	(6,720)
Subsidiary preferred stock dividends	(132)	(132)	(264)	(264)
Net Earnings Attributable to PNMR	27,678	21,512	38,304	38,592
Total Assets	5,403,906	5,252,589	5,403,906	5,252,589	5,372,583
Goodwill	278,297	278,297	278,297	278,297	278,297
Additions to utility and non-utility plant included in accounts payable	9,750	9,624	9,750	9,624
PNM Electric [Member]
Segment Reporting Information, Profit (Loss) [Abstract]
Electric operating revenues	279,690	260,094	537,583	510,510
Cost of energy	91,855	83,235	183,514	163,792
Margin	187,835	176,859	354,069	346,718
Other operating expenses	103,482	106,244	206,643	210,364
Depreciation and amortization	26,051	23,946	51,884	47,580
Operating income	58,302	46,669	95,542	88,774
Interest income	2,868	3,429	5,541	6,764
Other income (deductions)	3,360	(989)	4,766	3,995
Net interest charges	(19,890)	(18,928)	(39,847)	(37,422)
Earnings before Income Taxes	44,640	30,181	66,002	62,111
Income taxes (benefit)	14,943	9,841	21,532	20,694
Net Earnings	29,697	20,340	44,470	41,417
Valencia non-controlling interest	(3,573)	(3,455)	(6,777)	(6,720)
Subsidiary preferred stock dividends	(132)	(132)	(264)	(264)
Net Earnings Attributable to PNMR	25,992	16,753	37,429	34,433
Total Assets	4,185,189	4,069,375	4,185,189	4,069,375
Goodwill	51,632	51,632	51,632	51,632
Additions to utility and non-utility plant included in accounts payable	7,900	8,681	7,900	8,681
TNMP Electric [Member]
Segment Reporting Information, Profit (Loss) [Abstract]
Electric operating revenues	67,909	63,766	127,680	118,724
Cost of energy	13,804	11,484	26,851	22,773
Margin	54,105	52,282	100,829	95,951
Other operating expenses	22,159	21,319	44,148	41,908
Depreciation and amortization	12,279	12,066	23,960	23,353
Operating income	19,667	18,897	32,721	30,690
Interest income	0	0	0	0
Other income (deductions)	486	774	694	878
Net interest charges	(6,759)	(7,069)	(14,005)	(14,167)
Earnings before Income Taxes	13,394	12,602	19,410	17,401
Income taxes (benefit)	5,055	4,584	7,345	6,372
Net Earnings	8,339	8,018	12,065	11,029
Valencia non-controlling interest	0	0	0	0
Subsidiary preferred stock dividends	0	0	0	0
Net Earnings Attributable to PNMR	8,339	8,018	12,065	11,029
Total Assets	1,155,928	1,054,679	1,155,928	1,054,679
Goodwill	226,665	226,665	226,665	226,665
Additions to utility and non-utility plant included in accounts payable	1,101	551	1,101	551
Corporate and Other [Member]
Segment Reporting Information, Profit (Loss) [Abstract]
Electric operating revenues	0	0	0	0
Cost of energy	0	0	0	0
Margin	0	0	0	0
Other operating expenses	(3,207)	(4,582)	(6,910)	(7,906)
Depreciation and amortization	3,309	5,042	6,602	8,535
Operating income	(102)	(460)	308	(629)
Interest income	(35)	(43)	(74)	(86)
Other income (deductions)	(2,213)	(1,434)	(3,936)	(3,974)
Net interest charges	(3,967)	(4,201)	(8,062)	(8,176)
Earnings before Income Taxes	(6,317)	(6,138)	(11,764)	(12,865)
Income taxes (benefit)	336	(2,879)	(574)	(5,995)
Net Earnings	(6,653)	(3,259)	(11,190)	(6,870)
Valencia non-controlling interest	0	0	0	0
Subsidiary preferred stock dividends	0	0	0	0
Net Earnings Attributable to PNMR	(6,653)	(3,259)	(11,190)	(6,870)
Total Assets	62,789	128,535	62,789	128,535
Goodwill	0	0	0	0
Additions to utility and non-utility plant included in accounts payable	$ 749	$ 392	$ 749	$ 392