Stockholders' Equity (Options) (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014	Apr. 30, 2007
2007 Plan
Stockholders' Equity
Common stock reserved for issuance (in shares)				1,690,448
Number of shares available for future grants	0
Number of options
Balance at the end of the period (in shares)	1,054,096
2014 Plan
Stockholders' Equity
Common stock reserved for issuance (in shares)	2,045,495
Number of shares available for future grants	207,381
Inducement Plan
Stockholders' Equity
Number of shares awarded	330,000
Number of shares available for future grants	70,000
Grant period of stock awards	10 years
Vesting percentage	25.00%
Number of additional years of requisite service period	3 years
Vesting period	1 year
Minimum | Inducement Plan
Stockholders' Equity
Purchase price of awards expressed as a percentage of fair value of shares on the date of grant	100.00%
Vesting percentage	25.00%
Percentage of possible payouts of the target award	0.00%
Maximum | Inducement Plan
Stockholders' Equity
Percentage of possible payouts of the target award	100.00%
Stock options
Stockholders' Equity
Grant period of stock awards	10 years
Number of options
Balance at the beginning of period (in shares)	2,785,672	1,654,906
Options granted (in shares) | shares	571,753	1,253,216
Options exercised (in shares)	(478,099)	(36,189)
Options forfeited (in shares)	(92,349)	(86,261)
Balance at the end of the period (in shares)	2,786,977	2,785,672	1,654,906
Number of options vested and expected to vest (in shares)	2,786,977
Number of options vested and exercisable (in shares)	1,485,534
Weighted average exercise price
Balance at the beginning of period (in dollars per share)	$ 6.66	$ 4.25
Options granted (in dollars per share)	7.08	10.22
Options exercised (in dollars per share)	1.93	3.54
Options forfeited (in dollars per share)	15.35	13.38
Balance at the end of period (in dollars per share)	7.27	$ 6.66	$ 4.25
Weighted average exercise price, vested and expected to vest (in dollars per share)	7.27
Weighted average exercise price, vested and exercisable (in dollars per share)	$ 6.53
Additional information
Weighted average remaining contractual term	6 years 3 months 11 days	6 years 7 months 6 days	5 years 5 months 23 days
Weighted average remaining contractual term, vested and exercisable	4 years 6 months
Weighted average grant date fair value (in dollars per share)	$ 3.97	$ 4.60	$ 6.82
Stock-based compensation expense	$ 1,700	$ 2,000	$ 600
Number of years from the date of grant for tax benefits	2 years
Number of years from the date of exercise for tax benefits	1 year
Unrecognized compensation costs (in dollars)	$ 4,300
Weighted average period over which unrecognized compensation costs are expected to be recognized	2 years 8 months 27 days
Aggregate intrinsic value (in dollars)	$ 3	$ 600	$ 200
Stock options | Minimum
Stockholders' Equity
Purchase price of awards expressed as a percentage of fair value of shares on the date of grant	100.00%
Stock options | Maximum
Stockholders' Equity
Purchase price of awards expressed as a percentage of fair value of shares on the date of grant	110.00%
Percentage of voting power owned by shareholder	10.00%