Stockholder's Equity, Restricted Stock Units (Details) - Restricted Stock Units ("RSUs") [Member] $ / shares in Units, $ in Thousands	9 Months Ended	12 Months Ended
	Sep. 30, 2017 USD ($) $ / shares shares	Dec. 31, 2016 USD ($) $ / shares shares
Restricted stock units, number of shares [Roll Forward]
Outstanding RSUs, beginning of period (in shares) | shares	351,921
Awarded (in shares) | shares	102,880
Released (in shares) | shares	(151,886)
Forfeited (in shares) | shares	(146,165)
Outstanding RSUs, end of period (in shares) | shares	156,750	351,921
Restricted stock units, weighted average grant-date fair value [Roll forward]
Outstanding RSUs, beginning of period (in dollars per share) | $ / shares	$ 4.59
Awarded (in dollars per share) | $ / shares	2.43
Released (in dollars per share) | $ / shares	3.41
Forfeited (in dollars per share) | $ / shares	6.01
Outstanding RSUs, end of period (in dollars per share) | $ / shares	$ 3.00	$ 4.59
Restricted stock units, additional disclosures [Abstract]
Outstanding RSUs, weighted average remaining contractual term	11 months 12 days	1 year 22 days
Outstanding RSUs, aggregate intrinsic value | $	$ 368	$ 908
Compensation cost not yet recognized [Abstract]
Unrecognized compensation cost related to restricted stock units | $	$ 203
Weighted average period of recognition for unrecognized compensation cost	1 year 1 month 6 days