|
Property, Plant and Equipment - Additional Information (Detail) (USD $)
In Millions, unless otherwise specified |
3 Months Ended | 6 Months Ended | 12 Months Ended | ||
|---|---|---|---|---|---|
|
Mar. 31, 2014
|
Mar. 31, 2013
|
Jun. 30, 2013
Ocotillo [Member]
|
Jun. 30, 2013
Pattern Santa Isabel LLC [Member]
|
Dec. 31, 2012
Spring Valley [Member]
|
|
| Property, Plant and Equipment [Line Items] | |||||
| Depreciation expense related to property, plant and equipment | $ 20.8 | $ 22.3 | |||
| Cash grant received | 115.9 | 57.6 | 79.9 | ||
| Decrease in depreciation expense | $ 3.2 | $ 1.0 | |||