Stockholders' Equity - Restricted Stock Units (Details)	3 Months Ended
	Mar. 31, 2019 $ / shares shares
Restricted Stock Units
Outstanding at beginning of period (in shares) | shares	292,871
Granted (in shares) | shares	0
Canceled/forfeited (in shares) | shares	(119,896)
Outstanding at end of period (in shares) | shares	172,975
Weighted Average Grant Date Fair Value
Outstanding at beginning of period (in dollars per share) | $ / shares	$ 3.78
Granted (in dollars per share) | $ / shares	0.00
Canceled/forfeited (in dollars per share) | $ / shares	2.23
Outstanding at end of period (in dollars per share) | $ / shares	$ 4.86
Weighted Average Remaining Contractual Life (in years)
Outstanding at end of period	5 years 8 months
Restricted Stock Units
Restricted Stock Units
Outstanding at beginning of period (in shares) | shares	546,858
Granted (in shares) | shares	16,580
Released (in shares) | shares	(340,185)
Canceled/forfeited (in shares) | shares	(125,716)
Outstanding at end of period (in shares) | shares	97,537
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	2.61
Canceled/forfeited (in dollars per share) | $ / shares	2.26
Outstanding at end of period (in dollars per share) | $ / shares	$ 2.36
Weighted Average Remaining Contractual Life (in years)
Outstanding at end of period	1 year 1 month