Marketable Securities and Fair Value - Additional Information (Detail) - USD ($) shares in Millions |
3 Months Ended | 6 Months Ended | ||
|---|---|---|---|---|
Jun. 30, 2015 |
Jun. 30, 2014 |
Jun. 30, 2015 |
Jun. 30, 2014 |
|
| Schedule Of Available For Sale Securities [Line Items] | ||||
| Realized gain or losses | $ 0 | $ 0 | $ 0 | $ 0 |
| Weighted average maturity for available for sale securities | 4 months 3 days | |||
| February 2015 and March 2011 Offering | ||||
| Schedule Of Available For Sale Securities [Line Items] | ||||
| Shares of common stock to be purchased with warrants | 12.1 | 12.1 | ||
| Maximum | ||||
| Schedule Of Available For Sale Securities [Line Items] | ||||
| Available for sale securities, longest maturity date | 2016-05 | |||
| X | ||||||||||
- Definition Available for sale securities, longest maturity date. No definition available.
|
| X | ||||||||||
- Definition Weighted average maturity for available for sale securities. No definition available.
|
| X | ||||||||||
- Definition This item represents the difference between the gross realized gains and losses realized on the sale of debt or equity securities categorized neither as held-to-maturity nor trading securities. Additionally, this item would include any losses recognized for other than temporary impairments (OTTI) of the subject investments in debt and equity securities. Reference 1: http://www.xbrl.org/2003/role/presentationRef
|
| X | ||||||||||
- Definition Number of warrants or rights outstanding. Reference 1: http://www.xbrl.org/2003/role/presentationRef
|
| X | ||||||||||
- Definition Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table. No definition available.
|
| X | ||||||||||
- Details
|
| X | ||||||||||
- Details
|