v3.19.3.a.u2

Segment and geographic information - risk (Details) - Consolidated revenue | 12 Months Ended
--- | ---
Dec. 31, 2019 | Dec. 31, 2018 | Dec. 31, 2017
Georgia Power |  |  |
Consolidated revenue concentration |  |  |
Percentage of consolidated revenue | 11.10% | 10.90% |
Equistar Chemicals, LP |  |  |
Consolidated revenue concentration |  |  |
Percentage of consolidated revenue | 12.00% |  |
Independent Electricity System Operator |  |  |
Consolidated revenue concentration |  |  |
Percentage of consolidated revenue | 12.90% | 10.80% | 20.30%
Atlantic City Electric |  |  |
Consolidated revenue concentration |  |  |
Percentage of consolidated revenue |  | 12.60% |
San Diego Gas & Electric |  |  |
Consolidated revenue concentration |  |  |
Percentage of consolidated revenue |  |  | 10.60%
BC Hydro |  |  |
Consolidated revenue concentration |  |  |
Percentage of consolidated revenue |  | 12.50% | 10.30%
Niagara Mohawk |  |  |
Consolidated revenue concentration |  |  |
Percentage of consolidated revenue | 19.60% | 15.10% | 10.70%

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