| Selected Quarterly Financial Data (Unaudited) - Schedule of Quarterly Financial Information (Parenthetical) (Detail) (USD $) In Millions, unless otherwise specified | 3 Months Ended | 12 Months Ended | 
|---|---|---|
| Sep. 30, 2012 | Dec. 31, 2012 | |
| Schedule Of Quarterly Financial Data [Line Items] | ||
| Reduction of OFAC penalties and fines | $ 0.6 | $ 0.9 | 
| X | ||||||||||
| 
- Definition Reduction of previously recorded OFAC and BIS penalties and fines. No definition available. 
 | 
| X | ||||||||||
| 
- Details 
 |