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Equity - Stock Option Activity (Detail) (USD $)
In Thousands, except Share data, unless otherwise specified
3 Months Ended
Mar. 31, 2014
Number of Options  
Beginning balance (in shares) 1,828,613
Granted (in shares) 163,500
Exercised (in shares) (266,531)
Canceled (in shares) (3,500)
Ending balance (in shares) 1,722,082
Vested, at end of period (in shares) 959,139
Vested and expected to vest, at end of period (in shares) 1,439,049 [1]
Weighted Average Exercise Price  
Beginning balance (in USD per share) $ 16.46
Granted (in USD per share) $ 44.61
Exercised (in USD per share) $ 13.46
Canceled (in USD per share) $ 23.27
Ending balance (in USD per share) $ 19.59
Vested, at end of period (in USD per share) $ 14.12
Aggregate Intrinsic Value  
Exercised $ 7,673 [2]
Ending balance 47,929
Vested, at end of period 31,936 [3]
Vested and expected to vest, at end of period $ 41,625 [3]
Estimated forfeiture rate 16.00%
[1] Represents the number of vested options as of March 31, 2014, plus the number of unvested options expected to vest as of March 31, 2014, based on the unvested options outstanding as of March 31, 2014, adjusted for the estimated forfeiture rate of 16%.
[2] The aggregate intrinsic value was calculated based on the positive difference between the fair market value of the Company’s common stock as of the date of exercise and the exercise price of the underlying options.
[3] The aggregate intrinsic value was calculated based on the positive difference between the fair market value of the Company’s common stock as of March 31, 2014 and the exercise price of the underlying options.