Commitments and Contingencies (Spain Solar Projects) (Details) € in Millions, $ in Millions	12 Months Ended
	Dec. 31, 2015 USD ($)	Dec. 31, 2014 USD ($)	Dec. 31, 2015 EUR (€)
NEER [Member]
Loss Contingencies [Line Items]
Amount of debt outstanding under financing agreements related to Spain solar projects	$ 559
Amount of noncurrent derivative liability classified as current derivative liability due to event of default.	101
Capital Holdings [Member]
Loss Contingencies [Line Items]
Letters of Credit Outstanding, Amount	410
Standby Letters of Credit [Member] | Capital Holdings [Member]
Loss Contingencies [Line Items]
Letters of Credit Outstanding, Amount	15		€ 14
Line of Credit Facility, Maximum Borrowing Capacity	40		€ 37
Spain Solar Revenue Adjustment [Domain] | NEER [Member]
Loss Contingencies [Line Items]
Revenues	$ 17	$ (19)