Other Items - Summary of Interest and Other Financial (Costs) (Detail) - USD ($) $ in Millions |
3 Months Ended | 9 Months Ended | ||
|---|---|---|---|---|
Sep. 30, 2015 |
Sep. 30, 2014 |
Sep. 30, 2015 |
Sep. 30, 2014 |
|
| Other Income and Expenses [Abstract] | ||||
| Interest income | $ 0.1 | $ 0.0 | $ 0.2 | $ 0.0 |
| Interest expense | (5.9) | (1.2) | (18.0) | (3.1) |
| Interest capitalized | (1.2) | (0.2) | (2.6) | (0.7) |
| Other financial costs | (0.6) | (0.1) | (1.5) | (0.6) |
| Net interest and other financial costs | $ 5.2 | $ 1.1 | $ 16.7 | $ 3.0 |