Stockholders' Equity - Summary of Restricted Stock, Restricted Stock Unit and Performance-based Stock Unit Activity (Parenthetical) (Detail) - Performance-Based Stock Units [Member] |
6 Months Ended |
---|---|
Jun. 30, 2016
shares
| |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] | |
Performance-based stock units, percentage of attainment level | 100.00% |
Class A Common Stock [Member] | |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] | |
Performance-based stock units | 43 |