Schedule of Total Interest Expense Recognized Related to Notes (Detail) - USD ($) $ in Thousands |
3 Months Ended | 9 Months Ended | ||
|---|---|---|---|---|
Sep. 30, 2016 |
Sep. 30, 2015 |
Sep. 30, 2016 |
Sep. 30, 2015 |
|
| Debt Disclosure [Abstract] | ||||
| Contractual interest expense | $ 1,797 | $ 1,797 | $ 5,390 | $ 5,371 |
| Amortization of debt issuance costs | 311 | 302 | 928 | 900 |
| Total interest expense | $ 2,108 | $ 2,099 | $ 6,318 | $ 6,271 |