Acquisitions (Details) (USD $) In Millions, unless otherwise specified	0 Months Ended	1 Months Ended	0 Months Ended
	Feb. 19, 2015	Mar. 31, 2015	Feb. 24, 2015	Mar. 12, 2015	Apr. 15, 2015	Apr. 22, 2015	Apr. 30, 2015
Southern Power [Member] | Decatur Parkway Solar Project, LLC [Member]
Business Acquisition [Line Items]
Power of solar polycrystalline silicon facility (in MWs)	80
Life Output Of Plant	25 years
Southern Power [Member] | Decatur County Solar Project, LLC [Member]
Business Acquisition [Line Items]
Power of solar polycrystalline silicon facility (in MWs)	19
Life Output Of Plant	20 years
Southern Power [Member] | Decatur County Solar Projects [Member]
Business Acquisition [Line Items]
Beginning Year Of Output Of Constructed Plant	2015
Construction Capital Costs		$ 32
Southern Power [Member] | Decatur County Solar Projects [Member] | Minimum [Member]
Business Acquisition [Line Items]
Estimated Cost	200
Southern Power [Member] | Decatur County Solar Projects [Member] | Maximum [Member]
Business Acquisition [Line Items]
Estimated Cost	220
Southern Power [Member] | Kay Wind, LLC [Member]
Business Acquisition [Line Items]
Beginning Year Of Output Of Constructed Plant			2015
Life Output Of Plant			20 years
Energy From Wind-Powered Generating Facilities (in MWs)			299
Acquisition - cash consideration			492
Southern Power [Member] | Butler Solar LLC [Member]
Business Acquisition [Line Items]
Power of solar polycrystalline silicon facility (in MWs)				100
Beginning Year Of Output Of Constructed Plant				2016
Life Output Of Plant				30 years
Southern Power [Member] | Butler Solar LLC [Member] | Minimum [Member]
Business Acquisition [Line Items]
Estimated Cost				220
Southern Power [Member] | Butler Solar LLC [Member] | Maximum [Member]
Business Acquisition [Line Items]
Estimated Cost				230
Southern Power [Member] | Lost Hills Blackwell Holdings, LLC [Member] | Subsequent Event [Member]
Business Acquisition [Line Items]
Beginning Year Of Output Of Constructed Plant					2015
Life Output Of Plant					29 years
Acquisition - cash consideration					74
Southern Power [Member] | Lost Hills Blackwell Holdings, LLC [Member] | Class A Membership Interest [Member] | Subsequent Event [Member]
Business Acquisition [Line Items]
Noncontrolling Interest, Ownership Percentage by Parent					100.00%
Percentage Of Entitled Cash Distributions					51.00%
Southern Power [Member] | Lost Hills Solar Facility [Member] | Subsequent Event [Member]
Business Acquisition [Line Items]
Power of solar polycrystalline silicon facility (in MWs)					20
Southern Power [Member] | Blackwell Solar Facility [Member] | Subsequent Event [Member]
Business Acquisition [Line Items]
Power of solar polycrystalline silicon facility (in MWs)					12
Southern Power [Member] | LS Pawpaw, LLC [Member] | Subsequent Event [Member]
Business Acquisition [Line Items]
Power of solar polycrystalline silicon facility (in MWs)						30
Beginning Year Of Output Of Constructed Plant						2015
Life Output Of Plant						30 years
Southern Power [Member] | LS Pawpaw, LLC [Member] | Minimum [Member] | Subsequent Event [Member]
Business Acquisition [Line Items]
Estimated Cost						65
Southern Power [Member] | LS Pawpaw, LLC [Member] | Maximum [Member] | Subsequent Event [Member]
Business Acquisition [Line Items]
Estimated Cost						75
Southern Power [Member] | North Star [Member] | Subsequent Event [Member]
Business Acquisition [Line Items]
Power of solar polycrystalline silicon facility (in MWs)							60
Beginning Year Of Output Of Constructed Plant							2015
Life Output Of Plant							20 years
Acquisition - cash consideration							208
Southern Power [Member] | North Star [Member] | Class A Membership Interest [Member] | Subsequent Event [Member]
Business Acquisition [Line Items]
Noncontrolling Interest, Ownership Percentage by Parent							100.00%
Percentage Of Entitled Cash Distributions							51.00%
First Solar [Member] | Lost Hills Blackwell Holdings, LLC [Member] | Subsequent Event [Member]
Business Acquisition [Line Items]
Acquisition - cash consideration					34
First Solar [Member] | Lost Hills Blackwell Holdings, LLC [Member] | Class B Membership Interest [Member] | Subsequent Event [Member]
Business Acquisition [Line Items]
Noncontrolling Interest, Ownership Percentage by Parent					100.00%
Percentage Of Entitled Cash Distributions					49.00%
First Solar [Member] | North Star [Member] | Subsequent Event [Member]
Business Acquisition [Line Items]
Acquisition - cash consideration							$ 99
First Solar [Member] | North Star [Member] | Class B Membership Interest [Member] | Subsequent Event [Member]
Business Acquisition [Line Items]
Noncontrolling Interest, Ownership Percentage by Parent							100.00%
Percentage Of Entitled Cash Distributions							49.00%