Stockholders’ Equity

6 Months Ended

Jun. 30, 2019

Equity [Abstract]

Stockholders’ Equity

9. Stockholders’ Equity

The following tables present changes in stockholders’ equity for the six-month periods ended June 30, 2019 and 2018 (in thousands, except share data):

						Additional		Accumulated Other						Total
	Common					Paid-In		Comprehensive			Accumulated			Stockholders’
	Shares			Amount		Capital		Income (Loss)			Deficit			Equity (Deficit)
Balance at December 31, 2018		45,224,480		$	5	$	478,968	$	(28	)	$	(201,025	)	$	277,920
Retroactive adjustment to beginning    accumulated deficit for adoption of ASC 842		-			-		-		-			(320	)		(320	)
Issuance of common stock through at-the-market    offerings, net of issuance costs of $120		223,818			-		3,639		-			-			3,639
Exercise of stock options		30,800			-		360		-			-			360
Equity-based compensation		-			-		4,592		-			-			4,592
Other comprehensive gain		-			-		-		87			-			87
Net loss		-			-		-		-			(21,940	)		(21,940	)
Balance at March 31, 2019		45,479,098		$	5	$	487,559	$	59		$	(223,285	)	$	264,338
Issuance of common stock through at-the-market    offerings, net of issuance costs of $3		1,986,579			-		31,413		-			-			31,413
Exercise of stock options		203,072			-		1,664		-			-			1,664
Issuance of shares under employee stock    purchase plan		45,826			-		534		-			-			534
Equity-based compensation		-			-		4,404		-			-			4,404
Other comprehensive gain		-			-		-		196			-			196
Net loss		-			-		-		-			(25,683	)		(25,683	)
Balance at June 30, 2019		47,714,575		$	5	$	525,574	$	255		$	(248,968	)	$	276,866
						Additional		Accumulated Other						Total
	Common					Paid-In		Comprehensive			Accumulated			Stockholders’
	Shares			Amount		Capital		Income (Loss)			Deficit			Equity (Deficit)
Balance at December 31, 2017		42,384,623		$	4	$	421,706	$	-		$	(121,113	)	$	300,597
Retroactive adjustment to beginning    accumulated deficit for adoption of    ASU 2014-09		-			-		-		-			5,431			5,431
Exercise of stock options		709,321			-		6,720		-			-			6,720
Cancellation of restricted stock		(2,022	)		-		-		-			-			-
Equity-based compensation		-			-		4,107		-			-			4,107
Net loss		-			-		-		-			(21,356	)		(21,356	)
Balance at March 31, 2018		43,091,922		$	4	$	432,533	$	-		$	(137,038	)	$	295,499
Exercise of stock options		68,163			-		557		-			-			557
Issuance of shares under employee stock    purchase plan		32,707			-		598		-			-			598
Cancellation of restricted stock		(4,780	)		-		-		-			-			-
Equity-based compensation		-			-		4,901		-			-			4,901
Net loss		-			-		-		-			(22,219	)		(22,219	)
Balance at June 30, 2018		43,188,012		$	4	$	438,589	$	-		$	(159,257	)	$	279,336