Equity method investments in unconsolidated affiliates (Details) - USD ($) $ in Millions |
3 Months Ended | 6 Months Ended | ||
|---|---|---|---|---|
Jun. 30, 2016 |
Jun. 30, 2015 |
Jun. 30, 2016 |
Jun. 30, 2015 |
|
| Operating results | ||||
| Revenue | $ 30.6 | $ 33.0 | $ 63.7 | $ 70.8 |
| Project expenses | 22.5 | 23.9 | 44.5 | 50.6 |
| Project other expense | (0.5) | (0.5) | (0.9) | (0.9) |
| Project income (loss) | 7.6 | 8.6 | 18.3 | 19.3 |
| Chambers | ||||
| Operating results | ||||
| Revenue | 10.4 | 10.9 | 23.1 | 26.3 |
| Project expenses | 9.7 | 9.6 | 18.5 | 20.9 |
| Project other expense | (0.5) | (0.5) | (0.9) | (0.9) |
| Project income (loss) | 0.2 | 0.8 | 3.7 | 4.5 |
| Frederickson | ||||
| Operating results | ||||
| Revenue | 4.8 | 5.4 | 9.9 | 10.1 |
| Project expenses | 4.9 | 4.9 | 9.4 | 9.0 |
| Project income (loss) | (0.1) | 0.5 | 0.5 | 1.1 |
| Orlando | ||||
| Operating results | ||||
| Revenue | 13.2 | 14.1 | 26.7 | 26.9 |
| Project expenses | 6.0 | 6.7 | 12.6 | 13.3 |
| Project income (loss) | 7.2 | 7.4 | 14.1 | 13.6 |
| Other | ||||
| Operating results | ||||
| Revenue | 2.2 | 2.6 | 4.0 | 7.5 |
| Project expenses | 1.9 | 2.7 | $ 4.0 | 7.4 |
| Project income (loss) | $ 0.3 | $ (0.1) | $ 0.1 | |
| Other | Maximum | ||||
| Operating results | ||||
| Percentage of ownership interest | 10.00% | 10.00% | ||