Stock Options (Details 4) (USD $) In Thousands, except Per Share data, unless otherwise specified	12 Months Ended
Dec. 31, 2014	Dec. 31, 2013
Outstanding Stock Options (Fully Vested and Expected to Vest)
Number of outstanding options (in shares)	3,025
Weighted average remaining contractual life	3 years 11 months 9 days
Weighted average exercise price per share (in dollars per share)	$ 0.85
Intrinsic value (in thousands)	$ 6,032
Options that are Exercisable
Number of outstanding options (in shares)	2,511	2,396
Weighted average remaining contractual life	3 years 3 months 22 days
Weighted average exercise price per share (in dollars per share)	$ 0.78	$ 0.78
Intrinsic value (in thousands)	5,209
Additional disclosures
Total unrecognized compensation cost related to non-vested options	$ 248
Weighted average recognition period	9 months 11 days

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Weighted average period over which unrecognized compensation is expected to be recognized for equity-based compensation plans, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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Unrecognized cost of unvested options awarded to employees as compensation.

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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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Amount by which the current fair value of the underlying stock exceeds the exercise price of fully vested and expected to vest options outstanding.

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As of the balance sheet date, the number of shares into which fully vested and expected to vest stock options outstanding can be converted under the option plan.

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As of the balance sheet date, the weighted-average exercise price for outstanding stock options that are fully vested or expected to vest.

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Weighted average remaining contractual term for fully vested and expected to vest options outstanding, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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