Schedule I - Condensed Financial Information of Parent Company - Statements of Earnings (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Condensed Financial Statements, Captions [Line Items]
Operating Expenses									$ 1,084,966	$ 1,314,732	$ 1,136,156
Operating income	$ 63,584	$ 108,071	$ 64,822	$ 41,508	$ (119,138)	$ 121,505	$ 72,414	$ 49,569	277,985	124,350	299,697
Other Income and Deductions:
Other income									17,796	26,833	12,048
Net other income and deductions									45,822	36,663	20,577
Interest Charges									128,633	114,860	119,627
Earnings before Income Taxes									195,174	46,153	200,647
Income Taxes									63,278	15,075	69,738
Net Earnings Attributable to Company	$ 24,809	$ 54,418	$ 27,076	$ 10,546	$ (91,418)	$ 61,045	$ 31,673	$ 14,340	116,849	15,640	116,254
PNM Resources [Member]
Condensed Financial Statements, Captions [Line Items]
Operating Revenues									0	0	0
Operating Expenses									2,871	1,221	650
Operating income									(2,871)	(1,221)	(650)
Other Income and Deductions:
Equity in earnings of subsidiaries									122,252	27,352	124,543
Other income									1,711	747	622
Net other income and deductions									123,963	28,099	125,165
Interest Charges									8,102	8,275	13,650
Earnings before Income Taxes									112,990	18,603	110,865
Income Taxes									(3,859)	2,963	(5,389)
Net Earnings Attributable to Company									$ 116,849	$ 15,640	$ 116,254