SHARE BASED COMPENSATION (Tables)

3 Months Ended

Mar. 31, 2019

Equity [Abstract]

Schedule of service based restricted stock activity

The following table summarizes the Company’s service based restricted stock unit activity during the three months ended March 31, 2019:

	Number of Restricted Stock Units		Weighted Average Grant Date Fair Value
Unvested December 31, 2018	400,426		$	24.95
Granted	62,850		23.12
Vested	(24,769	)	20.88
Forfeited/canceled	(1,250	)	25.25
Unvested March 31, 2019	437,257		$	24.92

Schedule of performance based restricted stock activity

The following table summarizes the Company’s performance based restricted stock unit activity during the three months ended March 31, 2019:

	Number of Restricted Stock Units	Weighted Average Grant Date Fair Value
Unvested December 31, 2018	226,750	$	21.54
Granted	50,000	23.34
Vested	—	—
Forfeited/canceled	—	—
Unvested March 31, 2019	276,750	$	21.86

Schedule of stock option issuances and balances outstanding

The following table summarizes stock option activity during the three months ended March 31, 2019:

	Shares Underlying Options		Weighted Average Exercise Price		Weighted Average Remaining Contractual Life (years)	Aggregate Intrinsic Value (in thousands)
Outstanding at December 31, 2018	7,277,337		$	18.55	6.94	$	40,650
Granted	440,700		23.20
Exercised	(23,727	)	12.81
Forfeited/canceled	(33,134	)	24.94
Outstanding at March 31, 2019	7,661,176		$	18.81	6.87	$	40,435

Schedule of Share based compensation expenses

The following table sets forth total stock-based compensation for the three months ended March 31, 2019 and 2018 (in thousands):

	Three Months Ended March 31,
	2019		2018
Research and development	$	1,670	$	1,407
Selling, general & administrative	4,850		3,202
Total	$	6,520	$	4,609