Stock Incentive and Employee Stock Purchase Plans - Summary of Stock Option Activity (Detail) (USD $) In Thousands, except Per Share data, unless otherwise specified	12 Months Ended
Dec. 31, 2014	Dec. 31, 2013
Stock Options Outstanding
Options outstanding December 31, 2013	3,933	4,282
Granted	1,658	425
Exercised	(89)	(38)
Cancelled	(2,437)	(736)
Balance December 31, 2014	3,065	3,933
Options Exercisable, December 31, 2014	1,769
Weighted Average Exercise Price Per Option
Options outstanding December 31, 2013	$ 9.45	$ 10.25
Granted	$ 2.92	$ 2.10
Exercised	$ 2.17	$ 2.68
Cancelled	$ 10.52	$ 10.21
Balance December 31, 2014	$ 5.27	$ 9.45
Options Exercisable, December 31, 2014	$ 6.80
Weighted Average Remaining Contractual Term (Years), Options outstanding	4 years 11 months 1 day
Weighted Average Remaining Contractual Term (Years), Options Exercisable	4 years 11 months 27 days
Aggregate Intrinsic Value, Options outstanding	$ 1,022
Aggregate Intrinsic Value, Options Exercisable	$ 449

Amount of difference between fair value of the underlying shares reserved for issuance and exercise price of vested portions of options outstanding and currently exercisable.

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The number of shares into which fully or partially vested stock options outstanding as of the balance sheet date can be currently converted under the option plan.

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The weighted-average price as of the balance sheet date at which grantees can acquire the shares reserved for issuance on vested portions of options outstanding and currently exercisable under the stock option plan.

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Weighted average remaining contractual term for vested portions of options outstanding and currently exercisable or convertible, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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Number of options or other stock instruments for which the right to exercise has lapsed under the terms of the plan agreements.

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Gross number of share options (or share units) granted during the period.

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Amount by which the current fair value of the underlying stock exceeds the exercise price of options outstanding.

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Number of options outstanding, including both vested and non-vested options.

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Weighted average price at which grantees can acquire the shares reserved for issuance under the stock option plan.

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Weighted average remaining contractual term for option awards outstanding, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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Weighted average price at which option holders acquired shares when converting their stock options into shares.

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Weighted average price at which grantees could have acquired the underlying shares with respect to stock options of the plan that expired.

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Weighted average per share amount at which grantees can acquire shares of common stock by exercise of options.

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Number of share options (or share units) exercised during the current period.

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