Commitments and Contingencies (Details-1) - EPA [Member] - Legal Entity Type of Counterparty [Domain]	3 Months Ended
	Mar. 31, 2016 ppb pollutant phase state MW
Effluent Limitations Guidelines and Standards for Steam Electric Power Generating Source Category [Abstract]
Air pollution control and ash handling systems capacity at coal burning power plants, minimum (in MW) | MW	50
EPA's National Ambient Air Quality Standards
Number of pollutants monitored by the National Ambient Air Quality Standards | pollutant	6
Sulfur Dioxide NAAQS
Number of phases for attainment and nonattainment area designation | phase	3
Ozone NAAQS
Current primary regulated level of Ozone NAAQS (in parts per billion)	70
Current secondary regulated level of Ozone NAAQS (in parts per billion)	70
EPA's Cross State Air Pollution Rule
Number of states incorporating 2008 ozone NAAQS attainment levels | state	23