Summary of the Business and Significant Accounting Policies (Inventories/Depreciation and Amortization) (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Public Utilities, Inventory [Line Items]
Inventory, Net	$ 67,223	$ 59,643
Coal [Member]
Public Utilities, Inventory [Line Items]
Inventory, Net	24,872	19,231
Materials and supplies [Member]
Public Utilities, Inventory [Line Items]
Inventory, Net	42,351	40,412
Public Service Company of New Mexico [Member]
Public Utilities, Inventory [Line Items]
Inventory, Net	64,520	56,790
Public Service Company of New Mexico [Member] | Coal [Member]
Public Utilities, Inventory [Line Items]
Inventory, Net	24,872	19,231
Public Service Company of New Mexico [Member] | Materials and supplies [Member]
Public Utilities, Inventory [Line Items]
Inventory, Net	39,648	37,559
Public Service Company of New Mexico [Member] | Electric plant [Member]
Public Utilities, Inventory [Line Items]
Depreciation average rates used (as a percent)	2.27%	2.25%	2.24%
Public Service Company of New Mexico [Member] | Common, intangible, and general plant [Member]
Public Utilities, Inventory [Line Items]
Depreciation average rates used (as a percent)	4.87%	5.35%	6.03%
Texas-New Mexico Power Company [Member]
Public Utilities, Inventory [Line Items]
Inventory, Net	2,703	2,853
Depreciation average rates used (as a percent)	3.66%	3.56%	3.41%
Texas-New Mexico Power Company [Member] | Coal [Member]
Public Utilities, Inventory [Line Items]
Inventory, Net	0	0
Texas-New Mexico Power Company [Member] | Materials and supplies [Member]
Public Utilities, Inventory [Line Items]
Inventory, Net	$ 2,703	$ 2,853