Summary of Option Activity Under Stock Option Plans (Detail) - 2002 Stock Incentive Plan - USD ($) $ / shares in Units, $ in Thousands |
12 Months Ended | |||||
|---|---|---|---|---|---|---|
Dec. 31, 2016 |
Dec. 31, 2015 |
Dec. 31, 2014 |
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| Shares | ||||||
| Beginning Balance | 4,493,000 | 3,475,000 | 4,441,000 | |||
| Granted at fair market value | 3,113,000 | 1,931,000 | 240,000 | |||
| Granted at above fair market value | 1,340,000 | 369,000 | ||||
| Exercised | (1,000) | (38,000) | (153,000) | |||
| Forfeited, cancelled, or expired | (993,000) | (2,215,000) | (1,422,000) | |||
| Ending Balance | 6,612,000 | 4,493,000 | 3,475,000 | |||
| Options exercisable, December 31, 2016 | 3,352,000 | |||||
| Vested options expired during the 12 months ended December 31, 2016 | 387,000 | |||||
| Weighted-Average Exercise Price Per Share | ||||||
| Beginning Balance | $ 2.72 | $ 3.03 | $ 3.51 | |||
| Granted at fair market value | 1.42 | 2.22 | 2.23 | |||
| Granted at above fair market value | 2.46 | 3.05 | ||||
| Exercised | 0.82 | 1.15 | 2.03 | |||
| Forfeited, cancelled, or expired | 3.01 | 2.64 | 4.50 | |||
| Ending Balance | 2.06 | $ 2.72 | $ 3.03 | |||
| Options exercisable, December 31, 2016 | 2.50 | |||||
| Vested options expired during the 12 months ended December 31, 2016 | $ 4.11 | |||||
| Weighted-Average Remaining Contractual Term (Years) | ||||||
| Options outstanding | 7 years 8 months 12 days | |||||
| Options exercisable | 6 years 2 months 19 days | |||||
| Aggregate Intrinsic Value | ||||||
| Options outstanding | [1] | $ 178 | ||||
| Options exercisable | [1] | $ 63 | ||||
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