Acquisitions - Schedule of Acquisitions (Details) $ in Millions			3 Months Ended
	Apr. 08, 2016 USD ($) MW	Feb. 11, 2016 USD ($) MW	Dec. 31, 2016 USD ($) MW	Jun. 30, 2016 USD ($) MW	Mar. 31, 2016 USD ($)	Dec. 31, 2015 USD ($)
Business Acquisition [Line Items]
Construction work in progress					$ 9,406	$ 9,082
Southern Power [Member]
Business Acquisition [Line Items]
Construction work in progress					1,535	1,137
Business Combination, Contingent Consideration, Liability					21	$ 36
Southern Power [Member] | 70SM1 8ME, LCC (Calipatria) [Member]
Business Acquisition [Line Items]
Approx. Nameplate Capacity, Solar (MW) | MW		20
Southern Power Percentage Ownership		90.00%
PPA Contract Period		20 years
Approx. Purchase Price		$ 51
Southern Power [Member] | East Pecos [Member]
Business Acquisition [Line Items]
Construction work in progress					41
Southern Power [Member] | East Pecos [Member] | Minimum [Member]
Business Acquisition [Line Items]
Estimated Future Construction Payments					200
Southern Power [Member] | East Pecos [Member] | Maximum [Member]
Business Acquisition [Line Items]
Estimated Future Construction Payments					220
Southern Power [Member] | Turner Renewable Energy [Member]
Business Acquisition [Line Items]
Jointly Owned Utility Plant, Proportionate Ownership Share		10.00%
Southern Power and Turner Renewable Energy [Member] | 70SM1 8ME, LCC (Calipatria) [Member]
Business Acquisition [Line Items]
Approx. Purchase Price		$ 57
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Property, Plant, and Equipment					58
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Current Liabilities, Accounts Payable					2
Business Combination, Contingent Consideration, Liability		$ 6
Scenario, Forecast [Member] | Southern Power [Member] | Grant Wind, LLC [Member]
Business Acquisition [Line Items]
Approx. Nameplate Capacity, Wind (MW) | MW	151
Southern Power Percentage Ownership	100.00%
PPA Contract Period	20 years
Approx. Purchase Price	$ 258
Scenario, Forecast [Member] | Southern Power [Member] | East Pecos [Member]
Business Acquisition [Line Items]
Approx. Nameplate Capacity, Solar (MW) | MW			120
Southern Power Percentage Ownership			100.00%
PPA Contract Period			15 years
Approx. Purchase Price			$ 41
Scenario, Forecast [Member] | Southern Power [Member] | Desert Stateline Holdings, LLC [Member]
Business Acquisition [Line Items]
Approx. Nameplate Capacity, Solar (MW) | MW				40
Southern Power Percentage Ownership				100.00%
PPA Contract Period				15 years
Approx. Purchase Price				$ 127
Property, Plant and Equipment [Member] | Southern Power and Turner Renewable Energy [Member] | 70SM1 8ME, LCC (Calipatria) [Member]
Business Acquisition [Line Items]
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Assets					$ 1
Subsequent Event [Member] | Southern Power [Member] | Grant Wind, LLC [Member]
Business Acquisition [Line Items]
Business Combination, Contingent Consideration, Liability	$ 23
Period Of Operation For Performance Testing And Production	10 years