Share-Based Payment (Tables)

9 Months Ended

Sep. 30, 2014

The following weighted average assumptions were used in the estimated grant date fair value calculations for stock option awards:



	Nine months ended September 30,
	2013		2014
Risk free interest rate	1.06	%	1.83	%
Expected dividend yield	—	%	—	%
Expected stock price volatility	65.7	%	66.3	%
Average expected life (in years)	5.99		6.00

The following table summarizes the Company’s stock option activity:



	Number of Shares		Weighted- Average Exercise Price		Weighted- Average Remaining Contractual Term	Aggregate Intrinsic Value
Outstanding at December 31, 2013	803,617		$	20.83
Granted	45,783		28.97
Exercised	(72,794	)	6.31
Canceled	(135,547	)	12.26
Outstanding at September 30, 2014	641,059		$	21.66	6.01	$	4,657
Vested and expected to vest in the future at September 30, 2014	628,171		$	21.63	6.02	$	4,604
Exercisable at September 30, 2014	423,110		$	21.90	5.24	$	3,475

The following table summarizes the Company’s unvested stock option activity:



	Shares		Weighted-Average Grant-Date Fair Value
Unvested at December 31, 2013	376,024		$	8.10
Granted	45,783		17.56
Vested	(83,654	)	5.61
Canceled	(115,945	)	4.85
Unvested at September 30, 2014	222,208		$	12.61

The following table summarizes the Company’s restricted stock activity:



	Shares		Weighted-Average Grant-Date Fair Value
Unvested at December 31, 2013	70,891		$	7.01
Granted to employees	25,000		30.33
Granted to non-employee directors	—		—
Vested	(31,000	)	30.33
Canceled	(26,272	)	6.36
Unvested at September 30, 2014	38,619		$	28.36