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% |