Acquisitions - Schedule of Construction Projects (Details) $ in Millions	3 Months Ended		10 Months Ended
	Dec. 31, 2016 USD ($) MW	Sep. 30, 2016 MW	Sep. 30, 2016 USD ($) MW	May. 05, 2016 MW	Mar. 31, 2016 MW	Mar. 29, 2016	Dec. 31, 2015 MW
Southern Power [Member] | Desert Stateline Holdings, LLC [Member]
Business Acquisition [Line Items]
Capacity Of Small Power Production Facility | MW					76		110
Southern Power Percentage Ownership						15.00%
Class A Membership Interest [Member] | Southern Power [Member] | Desert Stateline Holdings, LLC [Member]
Business Acquisition [Line Items]
Percentage Of Entitled Cash Distributions						66.00%
Class A Membership Interest [Member] | Southern Power [Member] | Tranquillity, Roserock, Garland and Garland A [Member]
Business Acquisition [Line Items]
Southern Power Percentage Ownership					100.00%
Percentage Of Entitled Cash Distributions					51.00%
Class B Membership Interest [Member] | First Solar [Member] | Desert Stateline Holdings, LLC [Member]
Business Acquisition [Line Items]
Percentage Of Entitled Cash Distributions						34.00%
Class B Membership Interest [Member] | First Solar [Member] | Tranquillity, Roserock, Garland and Garland A [Member]
Business Acquisition [Line Items]
Southern Power Percentage Ownership					100.00%
Class B Membership Interest [Member] | Recurrent Energy [Member] | Tranquillity, Roserock, Garland and Garland A [Member]
Business Acquisition [Line Items]
Percentage Of Entitled Cash Distributions					49.00%
Scenario, Forecast [Member] | Southern Power [Member] | Sandhills [Member]
Business Acquisition [Line Items]
Approx. Nameplate Capacity, Solar (MW) | MW	146
PPA Contract Period	25 years
Scenario, Forecast [Member] | Southern Power [Member] | Sandhills [Member] | Minimum [Member]
Business Acquisition [Line Items]
Estimated Construction Costs	$ 260
Scenario, Forecast [Member] | Southern Power [Member] | Sandhills [Member] | Maximum [Member]
Business Acquisition [Line Items]
Estimated Construction Costs	$ 280
Scenario, Forecast [Member] | Southern Power [Member] | Butler Solar LLC [Member]
Business Acquisition [Line Items]
Approx. Nameplate Capacity, Solar (MW) | MW	103
PPA Contract Period	30 years
Scenario, Forecast [Member] | Southern Power [Member] | Butler Solar LLC [Member] | Minimum [Member]
Business Acquisition [Line Items]
Estimated Construction Costs	$ 220
Scenario, Forecast [Member] | Southern Power [Member] | Butler Solar LLC [Member] | Maximum [Member]
Business Acquisition [Line Items]
Estimated Construction Costs	$ 230
Scenario, Forecast [Member] | Southern Power [Member] | RE Garland Holdings, LLC [Member] | Minimum [Member]
Business Acquisition [Line Items]
PPA Contract Period	15 years
Scenario, Forecast [Member] | Southern Power [Member] | RE Tranquility Holdings, LLC [Member]
Business Acquisition [Line Items]
Approx. Nameplate Capacity, Solar (MW) | MW	205
PPA Contract Period	18 years
Scenario, Forecast [Member] | Southern Power [Member] | RE Tranquility Holdings, LLC [Member] | Minimum [Member]
Business Acquisition [Line Items]
Estimated Construction Costs	$ 473
Scenario, Forecast [Member] | Southern Power [Member] | RE Tranquility Holdings, LLC [Member] | Maximum [Member]
Business Acquisition [Line Items]
Estimated Construction Costs	$ 493
Scenario, Forecast [Member] | Southern Power [Member] | Desert Stateline Holdings, LLC [Member]
Business Acquisition [Line Items]
Capacity Of Small Power Production Facility | MW		75	75
Approx. Nameplate Capacity, Solar (MW) | MW		299	299
PPA Contract Period			20 years
Scenario, Forecast [Member] | Southern Power [Member] | Desert Stateline Holdings, LLC [Member] | Minimum [Member]
Business Acquisition [Line Items]
Estimated Construction Costs			$ 1,200
Scenario, Forecast [Member] | Southern Power [Member] | Desert Stateline Holdings, LLC [Member] | Maximum [Member]
Business Acquisition [Line Items]
Estimated Construction Costs			$ 1,300
Scenario, Forecast [Member] | Southern Power [Member] | RE Garland and Garland A Holdings, LLC [Member]
Business Acquisition [Line Items]
Approx. Nameplate Capacity, Solar (MW) | MW	205
Scenario, Forecast [Member] | Southern Power [Member] | RE Garland and Garland A Holdings, LLC [Member] | Minimum [Member]
Business Acquisition [Line Items]
Estimated Construction Costs	$ 532
Scenario, Forecast [Member] | Southern Power [Member] | RE Garland and Garland A Holdings, LLC [Member] | Maximum [Member]
Business Acquisition [Line Items]
Estimated Construction Costs	$ 552
Scenario, Forecast [Member] | Southern Power [Member] | RE Roserock Holdings, LLC [Member]
Business Acquisition [Line Items]
Approx. Nameplate Capacity, Solar (MW) | MW	160
PPA Contract Period	20 years
Scenario, Forecast [Member] | Southern Power [Member] | RE Roserock Holdings, LLC [Member] | Minimum [Member]
Business Acquisition [Line Items]
Estimated Construction Costs	$ 333
Scenario, Forecast [Member] | Southern Power [Member] | RE Roserock Holdings, LLC [Member] | Maximum [Member]
Business Acquisition [Line Items]
Estimated Construction Costs	$ 353
Scenario, Forecast [Member] | Southern Power [Member] | RE Garland and Garland A Holdings, LLC [Member] | Maximum [Member]
Business Acquisition [Line Items]
PPA Contract Period		20 years
Subsequent Event [Member] | Southern Power [Member] | Desert Stateline Holdings, LLC [Member]
Business Acquisition [Line Items]
Capacity Of Small Power Production Facility | MW				38