Commitments and Contingencies - Hazardous Air Pollutants Rulemaking (Details) - Public Service Company of New Mexico [Member] - San Juan Generating Station [Member] - MW	Dec. 31, 2016	Dec. 31, 2011
Public Utilities, General Disclosures [Line Items]
Minimum megawatt capacity from coal and oil-fired electric generating units under jurisdiction of the Mercury and Air Toxics Standards (in megawatts)		25
Mercury removal efficiency	99.00%