Segment Information (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013	Dec. 31, 2013
Segment Reporting Information, Profit (Loss) [Abstract]
Electric operating revenues	$ 346,160	$ 347,599	$ 675,057	$ 665,263
Cost of energy	109,419	105,659	222,033	210,365
Margin	236,741	241,940	453,024	454,898
Other operating expenses	123,282	122,434	248,845	243,881
Depreciation and amortization	42,163	41,639	84,130	82,446
Operating income	71,296	77,867	120,049	128,571
Interest income	2,040	2,833	4,158	5,467
Other income (deductions)	5,710	1,633	6,924	1,524
Net interest charges	(29,972)	(30,616)	(59,506)	(61,914)
Earnings before Income Taxes	49,074	51,717	71,625	73,648
Income taxes (benefit)	15,893	20,334	22,313	28,303
Segment earnings (loss)	33,181	31,383	49,312	45,345
Valencia non-controlling interest	(3,908)	(3,573)	(7,439)	(6,777)
Subsidiary preferred stock dividends	(132)	(132)	(264)	(264)
Segment earnings (loss) attributable to PNMR	29,141	27,678	41,609	38,304
Total Assets	5,604,192	5,403,906	5,604,192	5,403,906	5,500,210
Goodwill	278,297	278,297	278,297	278,297	278,297
PNM Electric [Member]
Segment Reporting Information, Profit (Loss) [Abstract]
Electric operating revenues	275,704	279,690	538,441	537,583
Cost of energy	92,642	91,855	189,268	183,514
Margin	183,062	187,835	349,173	354,069
Other operating expenses	106,233	103,482	213,957	206,643
Depreciation and amortization	27,023	26,051	54,105	51,884
Operating income	49,806	58,302	81,111	95,542
Interest income	2,065	2,868	4,193	5,541
Other income (deductions)	5,512	3,360	7,180	4,766
Net interest charges	(20,023)	(19,890)	(39,835)	(39,847)
Earnings before Income Taxes	37,360	44,640	52,649	66,002
Income taxes (benefit)	13,106	14,943	17,189	21,532
Segment earnings (loss)	24,254	29,697	35,460	44,470
Valencia non-controlling interest	(3,908)	(3,573)	(7,439)	(6,777)
Subsidiary preferred stock dividends	(132)	(132)	(264)	(264)
Segment earnings (loss) attributable to PNMR	20,214	25,992	27,757	37,429
Total Assets	4,290,529	4,185,189	4,290,529	4,185,189
Goodwill	51,632	51,632	51,632	51,632
TNMP Electric [Member]
Segment Reporting Information, Profit (Loss) [Abstract]
Electric operating revenues	70,456	67,909	136,616	127,680
Cost of energy	16,777	13,804	32,765	26,851
Margin	53,679	54,105	103,851	100,829
Other operating expenses	20,411	22,159	41,481	44,148
Depreciation and amortization	12,003	12,279	23,844	23,960
Operating income	21,265	19,667	38,526	32,721
Interest income	0	0	0	0
Other income (deductions)	514	486	702	694
Net interest charges	(6,655)	(6,759)	(13,252)	(14,005)
Earnings before Income Taxes	15,124	13,394	25,976	19,410
Income taxes (benefit)	5,590	5,055	9,640	7,345
Segment earnings (loss)	9,534	8,339	16,336	12,065
Valencia non-controlling interest	0	0	0	0
Subsidiary preferred stock dividends	0	0	0	0
Segment earnings (loss) attributable to PNMR	9,534	8,339	16,336	12,065
Total Assets	1,208,517	1,155,928	1,208,517	1,155,928
Goodwill	226,665	226,665	226,665	226,665
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	(3,362)	(3,207)	(6,593)	(6,910)
Depreciation and amortization	3,137	3,309	6,181	6,602
Operating income	225	(102)	412	308
Interest income	(25)	(35)	(35)	(74)
Other income (deductions)	(316)	(2,213)	(958)	(3,936)
Net interest charges	(3,294)	(3,967)	(6,419)	(8,062)
Earnings before Income Taxes	(3,410)	(6,317)	(7,000)	(11,764)
Income taxes (benefit)	(2,803)	336	(4,516)	(574)
Segment earnings (loss)	(607)	(6,653)	(2,484)	(11,190)
Valencia non-controlling interest	0	0	0	0
Subsidiary preferred stock dividends	0	0	0	0
Segment earnings (loss) attributable to PNMR	(607)	(6,653)	(2,484)	(11,190)
Total Assets	105,146	62,789	105,146	62,789
Goodwill	$ 0	$ 0	$ 0	$ 0