Equity method investments in unconsolidated affiliates (Details) - USD ($) $ in Millions |
3 Months Ended | 9 Months Ended | ||
|---|---|---|---|---|
Sep. 30, 2016 |
Sep. 30, 2015 |
Sep. 30, 2016 |
Sep. 30, 2015 |
|
| Operating results | ||||
| Revenue | $ 34.1 | $ 34.1 | $ 97.8 | $ 104.9 |
| Project expenses | 24.1 | 24.7 | 68.5 | 75.2 |
| Project other expense | (0.4) | (0.5) | (1.4) | (1.4) |
| Project income (loss) | 9.6 | 8.9 | 27.9 | 28.3 |
| Chambers | ||||
| Operating results | ||||
| Revenue | 11.2 | 11.0 | 34.3 | 37.3 |
| Project expenses | 9.3 | 9.2 | 27.8 | 30.2 |
| Project other expense | (0.4) | (0.5) | (1.4) | (1.4) |
| Project income (loss) | 1.5 | 1.3 | 5.1 | 5.7 |
| Frederickson | ||||
| Operating results | ||||
| Revenue | 5.8 | 5.8 | 15.7 | 15.9 |
| Project expenses | 4.9 | 5.1 | 14.3 | 14.1 |
| Project income (loss) | 0.9 | 0.7 | 1.4 | 1.8 |
| Orlando | ||||
| Operating results | ||||
| Revenue | 13.9 | 13.9 | 40.6 | 40.9 |
| Project expenses | 6.9 | 7.3 | 19.6 | 20.6 |
| Project income (loss) | 7.0 | 6.6 | 21.0 | 20.3 |
| Other | ||||
| Operating results | ||||
| Revenue | 3.2 | 3.4 | 7.2 | 10.8 |
| Project expenses | 3.0 | 3.1 | 6.8 | 10.3 |
| Project income (loss) | $ 0.2 | $ 0.3 | $ 0.4 | $ 0.5 |
| Other | Maximum | ||||
| Operating results | ||||
| Percentage of ownership interest | 10.00% | 10.00% | ||