Summary of Significant Accounting Policies - Schedule of Potential Weighted Common Shares Outstanding that were Excluded from Computation of Basic and Diluted Net Loss per Share of Common Stock (Detail) - shares |
12 Months Ended | ||
|---|---|---|---|
Dec. 31, 2016 |
Dec. 31, 2015 |
Dec. 31, 2014 |
|
| Employee share based awards [Member] | |||
| Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items] | |||
| Potential common shares excluded from computation of net loss per share | 12,091,473 | 15,592,736 | 14,729,749 |
| Convertible senior notes [Member] | |||
| Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items] | |||
| Potential common shares excluded from computation of net loss per share | 841,191 | 2,431,265 | 2,344,998 |
| Warrant issued in May 2013 [Member] | |||
| Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items] | |||
| Potential common shares excluded from computation of net loss per share | 262,702 | 1,049,791 | 921,985 |