Income Taxes Schedule of Effective Income Tax Rate Reconciliation (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Income Taxes [Line Items]
Federal income tax at statutory rates	$ 61,274	$ 61,262	$ 109,364
First Choice goodwill	0	0	15,055
Investment tax credits	(2,192)	(2,237)	(2,318)
Flow-through of depreciation items	1,132	1,284	3,659
Earnings attributable to non-controlling interest in Valencia	(5,082)	(4,918)	(4,917)
State income tax	3,818	4,646	3,395
Effective Income Tax Rate Reconciliation, Impairment of Production Tax Credits, Amount	3,880	718	0
Other	(3,317)	(5,845)	(2,703)
Total income taxes (benefit)	59,513	54,910	121,535
Effective tax rate	33.99%	31.37%	38.90%
Public Service Company of New Mexico [Member]
Income Taxes [Line Items]
Federal income tax at statutory rates	53,018	54,710	37,088
Investment tax credits	(2,192)	(2,237)	(2,318)
Flow-through of depreciation items	1,115	1,268	3,656
Earnings attributable to non-controlling interest in Valencia	(5,082)	(4,918)	(4,917)
State income tax	6,202	6,500	4,797
Other	(4,257)	(4,610)	(879)
Total income taxes (benefit)	48,804	50,713	37,427
Effective tax rate	32.22%	32.44%	35.32%
Texas-New Mexico Power Company [Member]
Income Taxes [Line Items]
Federal income tax at statutory rates	16,349	14,735	12,648
State income tax	1,247	1,185	1,288
Other	25	(568)	(55)
Total income taxes (benefit)	$ 17,621	$ 15,352	$ 13,881
Effective tax rate	37.72%	36.47%	38.41%