Stockholders' Equity - Restricted Stock Units (Details)	6 Months Ended
	Jun. 30, 2017 $ / shares shares
Restricted Stock Units
Outstanding at beginning of period (in shares) | shares	530,734
Granted (in shares) | shares	180,924
Canceled/forfeited (in shares) | shares	(282,869)
Outstanding at end of period (in shares) | shares	332,178
Weighted Average Grant Date Fair Value
Outstanding at beginning of period (in dollars per share) | $ / shares	$ 7.48
Granted (in dollars per share) | $ / shares	3.63
Canceled/forfeited (in dollars per share) | $ / shares	5.49
Outstanding at end of period (in dollars per share) | $ / shares	$ 7.17
Weighted Average Remaining Contractual Life (in years)
Outstanding at end of period	8 years 2 months 12 days
Restricted Stock Units
Restricted Stock Units
Outstanding at beginning of period (in shares) | shares	250,115
Granted (in shares) | shares	367,502
Released (in shares) | shares	(113,956)
Canceled/forfeited (in shares) | shares	(150,355)
Outstanding at end of period (in shares) | shares	353,306
Weighted Average Grant Date Fair Value
Outstanding at beginning of period (in dollars per share) | $ / shares	$ 6.34
Granted (in dollars per share) | $ / shares	3.20
Released (in dollars per share) | $ / shares	5.80
Canceled/forfeited (in dollars per share) | $ / shares	5.86
Outstanding at end of period (in dollars per share) | $ / shares	$ 3.45
Weighted Average Remaining Contractual Life (in years)
Outstanding at end of period	3 years 2 months 12 days