Commitments and Contingencies, Environmental Contingencies (Details)		1 Months Ended
	Mar. 31, 2012 New Mexico Greenhouse Gas (GHG) Regulations [Member]	Apr. 30, 2012 Electric Generating Unit (EGU) Mercury and Air Toxics Standards (MATS) Rule [Member] MW
Environmental Requirements [Abstract]
Number of regulations in New Mexico to limit GHG emissions which were repealed in 2012	2
Generating capacity (in MW)		25
Number of years before affected facilities must demonstrate compliance, low end of range (in years)		3Y
Number of years before affected facilities must demonstrate compliance, high end of range (in years)		4Y