Organization and Business - Schedule of Basic and Diluted Earnings per Share (Parenthetical) (Detail) - shares |
6 Months Ended | 12 Months Ended |
|---|---|---|
Jun. 30, 2013 |
Dec. 31, 2012 |
|
| Diluted weighted average units outstanding, contingently issuable units | 146,452 | |
| Class B Common Stock | ||
| Diluted weighted average units outstanding, contingently issuable units | 228,549 |