Share-Based Compensation (Details 1) (USD $)	6 Months Ended
Jun. 30, 2012
Summary of stock options activity
Beginning Balance, Option Shares Outstanding	934,816
Granted, Option Shares Outstanding	806,698
Exercised, Option Shares Outstanding	(13,510)
Forfeited, Option Shares Outstanding	(9,806)
Ending Balance, Option Shares Outstanding	1,718,198
Vested and expected to vest, Option Shares Outstanding	1,538,488
Vested, Option Shares Outstanding	304,425
Beginning Balance, Weighted Average Exercise Price	$ 4.88
Granted, Weighted Average Exercise Price	$ 23.58
Exercised, Weighted Average Exercise Price	$ 3.12
Forfeited, Weighted Average Exercise Price	$ 3.28
Ending Balance, Weighted Average Exercise Price	$ 13.68
Vested and expected to vest, Weighted Average Exercise Price	$ 13.01
Vested, Weighted Average Exercise Price	$ 1.87
Outstanding, Weighted Average Remaining Contractual Term (Years)	9 years 15 days
Vested and expected to vest, Weighted Average Remaining Contractual Term (Years)	8 years 11 months 27 days
Vested, Weighted Average Remaining Contractual Term (Years)	7 years 10 months 17 days
Outstanding, Aggregate Intrinsic Value	$ 15,697,604
Vested and expected to vest, Aggregate Intrinsic Value	14,959,224
Vested, Aggregate Intrinsic Value	$ 6,031,082

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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.

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

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

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The number of shares reserved for issuance under stock option agreements awarded under the plan that validly exist and are outstanding as of the balance sheet date, including 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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Amount of difference between fair value of the underlying shares reserved for issuance and exercise price of fully vested and expected to vest options that are exercisable.

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As of the balance sheet date, the weighted-average exercise price (at which grantees can acquire the shares reserved for issuance) for exercisable stock options that are fully vested or expected to vest.

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