Segment Information (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013	Dec. 31, 2013
Segment Reporting Information, Profit (Loss) [Abstract]
Electric operating revenues	$ 413,951	$ 399,730	$ 1,089,008	$ 1,064,993
Cost of energy	132,499	114,674	354,532	325,039
Margin	281,452	285,056	734,476	739,954
Other operating expenses	120,358	124,574	369,203	368,454
Depreciation and amortization	44,295	42,743	128,424	125,189
Operating income	116,799	117,739	236,849	246,311
Interest income	2,084	2,264	6,241	7,731
Other income (deductions)	1,773	(528)	8,697	996
Net interest charges	(30,115)	(30,365)	(89,621)	(92,279)
Earnings before Income Taxes	90,541	89,110	162,166	162,759
Income taxes (benefit)	31,055	30,296	53,368	58,600
Segment earnings (loss)	59,486	58,814	108,798	104,159
Valencia non-controlling interest	(3,701)	(4,127)	(11,140)	(10,904)
Dividends declared on preferred stock	(132)	(132)	(396)	(396)
Segment earnings (loss) attributable to PNMR	55,653	54,555	97,262	92,859
Total Assets	5,709,209	5,428,814	5,709,209	5,428,814	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	334,993	326,026	873,434	863,609
Cost of energy	115,097	100,200	304,365	283,715
Margin	219,896	225,826	569,069	579,894
Other operating expenses	101,757	104,730	315,714	311,372
Depreciation and amortization	27,524	25,879	81,629	77,763
Operating income	90,615	95,217	171,726	190,759
Interest income	2,102	2,298	6,295	7,839
Other income (deductions)	1,569	2,211	8,749	6,977
Net interest charges	(20,092)	(20,124)	(59,927)	(59,971)
Earnings before Income Taxes	74,194	79,602	126,843	145,604
Income taxes (benefit)	25,142	27,652	42,331	49,184
Segment earnings (loss)	49,052	51,950	84,512	96,420
Valencia non-controlling interest	(3,701)	(4,127)	(11,140)	(10,904)
Dividends declared on preferred stock	(132)	(132)	(396)	(396)
Segment earnings (loss) attributable to PNMR	45,219	47,691	72,976	85,120
Total Assets	4,358,474	4,192,470	4,358,474	4,192,470	4,227,616
Goodwill	51,632	51,632	51,632	51,632	51,632
Tnmp Electric [Member]
Segment Reporting Information, Profit (Loss) [Abstract]
Electric operating revenues	78,958	73,704	215,574	201,384
Cost of energy	17,402	14,474	50,167	41,324
Margin	61,556	59,230	165,407	160,060
Other operating expenses	22,251	23,126	63,732	67,274
Depreciation and amortization	13,432	13,850	37,276	37,810
Operating income	25,873	22,254	64,399	54,976
Interest income	0	0	0	0
Other income (deductions)	793	716	1,495	1,409
Net interest charges	(6,870)	(6,655)	(20,122)	(20,661)
Earnings before Income Taxes	19,796	16,315	45,772	35,724
Income taxes (benefit)	7,441	6,209	17,081	13,554
Segment earnings (loss)	12,355	10,106	28,691	22,170
Valencia non-controlling interest	0	0	0	0
Dividends declared on preferred stock	0	0	0	0
Segment earnings (loss) attributable to PNMR	12,355	10,106	28,691	22,170
Total Assets	1,216,545	1,162,587	1,216,545	1,162,587	1,162,431
Goodwill	226,665	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	(3,650)	(3,282)	(10,243)	(10,192)
Depreciation and amortization	3,339	3,014	9,519	9,616
Operating income	311	268	724	576
Interest income	(18)	(34)	(54)	(108)
Other income (deductions)	(589)	(3,455)	(1,547)	(7,390)
Net interest charges	(3,153)	(3,586)	(9,572)	(11,647)
Earnings before Income Taxes	(3,449)	(6,807)	(10,449)	(18,569)
Income taxes (benefit)	(1,528)	(3,565)	(6,044)	(4,138)
Segment earnings (loss)	(1,921)	(3,242)	(4,405)	(14,431)
Valencia non-controlling interest	0	0	0	0
Dividends declared on preferred stock	0	0	0	0
Segment earnings (loss) attributable to PNMR	(1,921)	(3,242)	(4,405)	(14,431)
Total Assets	134,190	73,757	134,190	73,757
Goodwill	$ 0	$ 0	$ 0	$ 0