Acquisitions - Construction Projects (Details) - MW							1 Months Ended							8 Months Ended	12 Months Ended
	Jul. 01, 2016	Mar. 04, 2016	Dec. 17, 2015	Nov. 23, 2015	Aug. 31, 2015	Aug. 28, 2015	Dec. 31, 2016	Nov. 30, 2016	Oct. 31, 2016	Aug. 31, 2016	Jul. 31, 2016	Mar. 31, 2016	Feb. 29, 2016	Jul. 31, 2016	Dec. 31, 2016	Dec. 31, 2015	Mar. 29, 2016
Southern Power [Member]
Business Acquisition [Line Items]
Life Output Of Plant																20 years
Southern Power [Member] | East Pecos [Member]
Business Acquisition [Line Items]
Power of Solar Polycrystalline Silicon Facility		120
Life Output Of Plant		15 years
Noncontrolling Interest, Ownership Percentage by Parent		100.00%
Southern Power [Member] | Butler Solar LLC [Member]
Business Acquisition [Line Items]
Power of Solar Polycrystalline Silicon Facility							103								103
Life Output Of Plant							30 years
Southern Power [Member] | Butler Solar Farm, LLC [Member]
Business Acquisition [Line Items]
Power of Solar Polycrystalline Silicon Facility													22
Life Output Of Plant													20 years
Southern Power [Member] | Desert Stateline Holdings, LLC [Member]
Business Acquisition [Line Items]
Power of Solar Polycrystalline Silicon Facility					299		299				299			299	299
Life Output Of Plant					20 years									20 years
Noncontrolling Interest, Ownership Percentage by Parent					51.00%												15.00%
Southern Power [Member] | RE Garland Holdings, LLC [Member]
Business Acquisition [Line Items]
Power of Solar Polycrystalline Silicon Facility									185
Life Output Of Plant			20 years						15 years
Southern Power [Member] | RE Garland A Holdings, LLC [Member]
Business Acquisition [Line Items]
Power of Solar Polycrystalline Silicon Facility										20
Life Output Of Plant			15 years							20 years
Southern Power [Member] | LS Pawpaw, LLC [Member]
Business Acquisition [Line Items]
Power of Solar Polycrystalline Silicon Facility												30
Life Output Of Plant												30 years
Southern Power [Member] | RE Roserock Holdings, LLC [Member]
Business Acquisition [Line Items]
Power of Solar Polycrystalline Silicon Facility				160				160
Life Output Of Plant				20 years				20 years
Noncontrolling Interest, Ownership Percentage by Parent				51.00%
Southern Power [Member] | Sandhills [Member]
Business Acquisition [Line Items]
Power of Solar Polycrystalline Silicon Facility									146
Life Output Of Plant									25 years
Southern Power [Member] | RE Tranquility Holdings, LLC [Member]
Business Acquisition [Line Items]
Power of Solar Polycrystalline Silicon Facility						205					205			205
Life Output Of Plant						18 years					18 years
Noncontrolling Interest, Ownership Percentage by Parent						51.00%
Southern Power [Member] | Lamesa [Member]
Business Acquisition [Line Items]
Power of Solar Polycrystalline Silicon Facility	102
Life Output Of Plant	15 years
Noncontrolling Interest, Ownership Percentage by Parent	100.00%
Southern Power [Member] | Mankato Expansion [Member]
Business Acquisition [Line Items]
Capacity of Natural Gas Facility							345								345
Life Output Of Plant															20 years
Southern Power [Member] | Rutherford [Member]
Business Acquisition [Line Items]
Power of Solar Polycrystalline Silicon Facility	74
Life Output Of Plant	15 years
Noncontrolling Interest, Ownership Percentage by Parent	90.00%
Turner Renewable Energy [Member] | Rutherford [Member]
Business Acquisition [Line Items]
Noncontrolling Interest, Ownership Percentage by Parent	10.00%