Stockholders' Equity - Restricted Stock Units (Details)	6 Months Ended
	Jun. 30, 2019 $ / shares shares
Restricted Stock Units
Outstanding at beginning of period (in shares) | shares	292,871
Canceled/forfeited (in shares) | shares	(129,896)
Outstanding at end of period (in shares) | shares	162,975
Weighted Average Grant Date Fair Value
Outstanding at beginning of period (in dollars per share) | $ / shares	$ 3.78
Canceled/forfeited (in dollars per share) | $ / shares	2.67
Outstanding at end of period (in dollars per share) | $ / shares	$ 4.67
Weighted Average Remaining Contractual Life (in years)
Outstanding at end of period	5 years 6 months
Restricted Stock Units
Restricted Stock Units
Outstanding at beginning of period (in shares) | shares	546,858
Granted (in shares) | shares	27,187
Released (in shares) | shares	(377,894)
Canceled/forfeited (in shares) | shares	(152,441)
Outstanding at end of period (in shares) | shares	43,710
Weighted Average Grant Date Fair Value
Outstanding at beginning of period (in dollars per share) | $ / shares	$ 2.54
Granted (in dollars per share) | $ / shares	1.16
Released (in dollars per share) | $ / shares	2.54
Canceled/forfeited (in dollars per share) | $ / shares	2.32
Outstanding at end of period (in dollars per share) | $ / shares	$ 2.62
Weighted Average Remaining Contractual Life (in years)
Outstanding at end of period	1 year 6 months