Income Taxes Interest Income (Expense) Related to Income Taxes (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Income Taxes [Line Items]
Interest income related to income taxes	$ 0	$ 146	$ 242
Public Service Company of New Mexico [Member]
Income Taxes [Line Items]
Interest income related to income taxes	0	148	251
Texas-New Mexico Power Company [Member]
Income Taxes [Line Items]
Interest income related to income taxes	$ 0	$ (2)	$ (2)