Certain Balance Sheet Accounts - Summary of Property and Equipment (Detail) - USD ($) $ in Thousands |
Dec. 31, 2016 |
Dec. 31, 2015 |
|---|---|---|
| Property Plant And Equipment [Line Items] | ||
| Total property and equipment | $ 77,498 | $ 76,163 |
| Less accumulated depreciation | 53,604 | 48,594 |
| Total | 23,894 | 27,569 |
| Computers and Equipment [Member] | ||
| Property Plant And Equipment [Line Items] | ||
| Total property and equipment | 17,137 | 18,177 |
| Computer Software [Member] | ||
| Property Plant And Equipment [Line Items] | ||
| Total property and equipment | 26,686 | 23,899 |
| Furniture and Fixtures [Member] | ||
| Property Plant And Equipment [Line Items] | ||
| Total property and equipment | 8,471 | 8,527 |
| Leasehold Improvements [Member] | ||
| Property Plant And Equipment [Line Items] | ||
| Total property and equipment | $ 25,204 | $ 25,560 |