|
Share-Based Payment - Additional Information (Detail) (USD $)
In Millions, unless otherwise specified |
3 Months Ended | 9 Months Ended | ||
|---|---|---|---|---|
|
Sep. 30, 2012
|
Sep. 30, 2011
|
Sep. 30, 2012
|
Sep. 30, 2011
|
|
| Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items] | ||||
| Payments made under share based compensation | $ 0 | $ 0 | ||
| Change in accrual for share-based compensation expenses | $ 1.3 | $ 0.1 | $ 1.8 | $ 0.1 |