Equity Compensation (Tables)

3 Months Ended

Mar. 31, 2019

Equity Compensation

Summary of stock option activity

				Weighted
				Average
	Shares Subject	Weighted		Remaining
	to Options	Average		Contractual
	Outstanding	Exercise Price		Life (Years)
Balance at December 31, 2018	1,081,212		12.98
Exercised	(32,010)		9.70
Expired	(2,626)		16.96
Forfeited	(1,336)		7.28
Balance at March 31, 2019	1,045,240		13.08
Exercisable options at March 31, 2019	1,010,354		13.21	4.4
Vested and expected to vest at March 31, 2019	1,045,240		13.08	4.4

Summary of stock options outstanding and exercisable

The following table summarizes information about stock options outstanding and exercisable at March 31, 2019:

				Options Outstanding				Options Exercisable
							Weighted-		Weighted-
				Weighted			Average		Average
				Average		Number of	Remaining	Number of	Remaining
				Exercise		Underlying	Contractual	Underlying	Contractual
Range of Exercise Prices				Price		Shares	Life (in years)	Shares	Life (in years)
$	4.89	-	7.49		6.22	269,614	2.4	267,480	2.3
$	8.16	-	12.93		10.57	274,926	4.9	242,174	4.8
$	12.98	-	19.56		15.60	270,481	5.6	270,481	5.6
$	20.91	-	22.92		21.16	230,219	4.8	230,219	4.8
						1,045,240		1,010,354

Summary of aggregate intrinsic-value of options exercised, outstanding and exercisable

The following table summarizes the aggregate intrinsic-value of options exercised, exercisable and vested and expected to vest (in thousands):

	For the Three Months Ended
	and as of March 31,
	2019		2018
Options Exercised	$	269	$	2,765
Options Exercisable		4,757		15,335
Options Vested and Expected to Vest		5,026		17,203

Summary of restricted stock unit activity

	Number of	Weighted Average
	Shares	Grant Date Fair Value
Non-vested balance at December 31, 2018	824,365	$	19.77
Awarded	808,520		17.69
Vested	(314,606)		19.07
Forfeited	(9,002)		19.39
Non-vested balance at March 31, 2019	1,309,277		18.66

Schedule of total stock-based compensation expense classified in Statements of Operations

Total stock-based compensation expense has been classified as follows in the accompanying condensed consolidated statements of operations (in thousands):

	Three Months Ended
	March 31,
	2019		2018
Cost of revenue	$	78	$	68
Research and development		1,287		1,084
Sales and marketing		870		959
General and administrative		1,294		1,224
Total stock-based compensation expense	$	3,529	$	3,335