v3.5.0.2

Segment and geographic information - Risk (Details) - Revenues, net - Consolidated revenue	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Independent Electricity System Operator
Consolidated revenue concentration
Percentage of consolidated revenue	24.50%	22.90%	28.00%	27.70%
San Diego Gas & Electric
Consolidated revenue concentration
Percentage of consolidated revenue	16.10%	16.70%	11.50%	12.60%
BC Hydro
Consolidated revenue concentration
Percentage of consolidated revenue	10.60%	9.10%	11.60%	7.70%
Georgia Power
Consolidated revenue concentration
Percentage of consolidated revenue	10.90%	10.20%		10.40%

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+ References

No definition available.

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+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
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