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Acquisitions - Narrative (Details) $ in Millions				6 Months Ended
Acquisitions - Narrative (Details) $ in Millions	Apr. 30, 2015 USD ($) MW	Apr. 15, 2015 USD ($) MW	Feb. 24, 2015 USD ($) MW	Jun. 30, 2015 USD ($) MW
Southern Power [Member]
Business Acquisition [Line Items]
Life Output Of Plant				25 years
Power of solar polycrystalline silicon facility (in MWs) \| MW				146
Number of Businesses Acquired				5
Total Cost				$ 188
Southern Power [Member] \| SG2 Holdings, LLC [Member]
Business Acquisition [Line Items]
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Property, Plant, and Equipment				707
Prepaid Long Term Service Agreements				20
Southern Power [Member] \| Kay Wind, LLC [Member]
Business Acquisition [Line Items]
Payments to Acquire Businesses, Gross			$ 492
Energy From Wind-Powered Generating Facilities (in MWs) \| MW			299
Beginning Year Of Output Of Constructed Plant			2015
Life Output Of Plant			20 years
Southern Power [Member] \| Lost Hills Blackwell Holdings, LLC [Member]
Business Acquisition [Line Items]
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Property, Plant, and Equipment				98
Prepaid Long Term Service Agreements				9
Payments to Acquire Businesses, Gross		$ 74
Beginning Year Of Output Of Constructed Plant		2015
Life Output Of Plant		29 years
Southern Power [Member] \| Lost Hills Blackwell Holdings, LLC [Member] \| Class A Membership Interest [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]
Business Acquisition [Line Items]
Power of solar polycrystalline silicon facility (in MWs) \| MW		22
Southern Power [Member] \| Blackwell Solar Facility [Member]
Business Acquisition [Line Items]
Power of solar polycrystalline silicon facility (in MWs) \| MW		13
Southern Power [Member] \| North Star [Member]
Business Acquisition [Line Items]
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Property, Plant, and Equipment				266
Prepaid Long Term Service Agreements				21
Payments to Acquire Businesses, Gross	$ 211
Life Output Of Plant	20 years
Power of solar polycrystalline silicon facility (in MWs) \| MW	61
Purchased Power Agreement Intangible				$ 24
Southern Power [Member] \| North Star [Member] \| Class A Membership Interest [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]
Business Acquisition [Line Items]
Payments to Acquire Businesses, Gross		$ 33
First Solar [Member] \| Lost Hills Blackwell Holdings, LLC [Member] \| Class B Membership Interest [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]
Business Acquisition [Line Items]
Payments to Acquire Businesses, Gross	$ 100
First Solar [Member] \| North Star [Member] \| Class B Membership Interest [Member]
Business Acquisition [Line Items]
Noncontrolling Interest, Ownership Percentage by Parent	100.00%
Percentage Of Entitled Cash Distributions	49.00%