Stock-based Compensation - Options (Details) - Options [Member] - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015	Dec. 31, 2015
Number of options outstanding [Roll Forward]
Options outstanding, beginning of period (in shares)			3,779,000
Granted (in shares)	0	0	68,000	20,000
Exercised (in shares)			(169,000)
Canceled and expired (in shares)			(536,000)
Options outstanding, end of period (in shares)	3,142,000		3,142,000		3,779,000
Options vested and unvested options expected to vest, net of forfeitures, end of period (in shares)	3,084,000		3,084,000
Options exercisable, end of period (in shares)	1,825,000		1,825,000
Weighted average exercise price [Roll Forward]
Options outstanding, beginning of period (in dollars per share)			$ 2.97
Granted (in dollars per share)			2.56
Exercised (in dollars per share)			2.52
Canceled and expired (in dollars per share)			3.21
Options outstanding, end of period (in dollars per share)	$ 2.94		2.94		$ 2.97
Options vested as of March 31, 2015 and unvested options expected to vest, net of forfeitures (in dollars per share)	2.96		2.96
Options exercisable, end of period (in dollars per share)	$ 3.43		$ 3.43
Weighted average Remaining Contractual Life [Abstract]
Options outstanding			6 years 7 months 24 days		6 years 3 months 4 days
Options vested and unvested options expected to vest, net of forfeitures, end of period			6 years 7 months 10 days
Option exercisable, end of period			5 years 2 months 19 days
Aggregate Intrinsic Value [Abstract]
Options outstanding, beginning of period			$ 764
Options outstanding, end of period	$ 7,319		7,319		$ 764
Options vested and expected to vest, end of period	7,149		7,149
Options exercisable, end of period	$ 3,479		$ 3,479
Closing price (in dollars per share)	$ 5.19		$ 5.19