Commitments and Contingencies (Spain Solar Projects) (Details) In Millions, unless otherwise specified	Mar. 31, 2014 NextEra Energy Resources [Member] USD ($)	Mar. 31, 2014 Standby Letters of Credit [Member] Capital Holdings [Member] USD ($)	Mar. 31, 2014 Standby Letters of Credit [Member] Capital Holdings [Member] EUR (€)	Mar. 31, 2014 Performance Guarantee [Member] Capital Holdings [Member] USD ($)	Mar. 31, 2014 Performance Guarantee [Member] Capital Holdings [Member] EUR (€)
Loss Contingencies [Line Items]
Letters of Credit Outstanding, Amount		$ 51	€ 37	$ 14	€ 10
Amount of debt outstanding under financing agreements related to Spain solar projects	792
Amount of noncurrent derivative liability classified as current derivative liability due to event of default	$ 108