Stock Options, Stock Purchase Plan and Warrants - Status of Our Stock Options and Stock Awards (Detail) (USD $)	12 Months Ended
Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Stock options, beginning balance	5,725,298	5,777,212	4,779,170
Weighted average exercise price, beginning balance	$ 1.22	$ 1.02	$ 0.87
Stock options, granted	760,500	416,000	1,298,000
Stock options, exercised	(2,387,327)	(438,998)	(197,209)
Stock options, cancelled	(86,375)	(28,916)	(102,749)
Stock options, ending balance	4,012,096	5,725,298	5,777,212
Stock options, exercisable, ending balance	2,379,378
Weighted average exercise price, granted	$ 4.21	$ 3.66	$ 1.64
Weighted average exercise price, exercised	$ 0.76	$ 0.85	$ 1.02
Weighted average exercise price, cancelled	$ 2.39	$ 1.47	$ 1.60
Weighted average exercise price, ending balance	$ 2.04	$ 1.22	$ 1.02
Weighted average exercise price, exercisable, ending balance	$ 1.27

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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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-Publisher FASB

-Name Accounting Standards Codification

-Topic 718

-SubTopic 10

-Section 50

-Paragraph 2

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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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The number of shares under options that were cancelled during the reporting period as a result of occurrence of a terminating event specified in contractual agreements pertaining to the stock option plan.

+ References

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

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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 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 that were terminated.

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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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