Acquisitions (Details) (Southern Power [Member], USD $) In Millions, unless otherwise specified	0 Months Ended		0 Months Ended		0 Months Ended		0 Months Ended
	Apr. 17, 2014 Adobe Solar LLC [Member]	Apr. 17, 2014 Adobe Solar LLC [Member] MW	May 22, 2014 Macho Springs LLC [Member]	May 22, 2014 Macho Springs LLC [Member] MW	Nov. 06, 2014 Subsequent Event [Member] Solar Gen 2 Imperial Valley, LLC [Member]	Nov. 06, 2014 Subsequent Event [Member] Solar Gen 2 Imperial Valley, LLC [Member] MW	Nov. 06, 2014 Subsequent Event [Member] First Solar [Member]	Nov. 06, 2014 Class A Membership Interest [Member] Subsequent Event [Member] Solar Gen 2 Imperial Valley, LLC [Member]	Nov. 06, 2014 Class B Membership Interest [Member] Subsequent Event [Member] Solar Gen 2 Imperial Valley, LLC [Member]
Business Acquisition [Line Items]
Noncontrolling Interest, Ownership Percentage by Parent		90.00%						100.00%	100.00%
Power of solar polycrystalline silicon facility		20		50		150
Beginning Year Of Output Of Constructed Plant	2014		2014
Life Output Of Plant	20 years		20 years		25 years
Acquisition - cash consideration	$ 96.2		$ 130.0		$ 508.0		$ 128.0
Acquisition - property, plant and equipment		83.5
Acquisition - receivables related to reimbursable transmission costs		14.5
Acquisition - PPA intangible		6.3
Acquisition - bargain purchase gain	5.1
Acquisition - deferred tax liability		$ 2.9
Percentage Of Entitled Cash Distributions								51.00%	49.00%