Stock Based Compensation - Exercise Price Range (Details) - $ / shares shares in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Number of Options, Outstanding and Exercisable (in shares)	1,202	1,222	1,269
Weighted Average Remaining Contractual Life (In Years)	4 years 10 months 22 days
Weighted Average Exercise Price, Outstanding and Exercisable (in dollars per share)	$ 1.99	$ 1.99	$ 1.98
$0.90 – $1.44
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Range of price, lower range limit (in dollars per share)	0.90
Range of price, upper range limit (in dollars per share)	$ 1.44
Number of Options, Outstanding and Exercisable (in shares)	56
Weighted Average Remaining Contractual Life (In Years)	4 years 11 months 19 days
Weighted Average Exercise Price, Outstanding and Exercisable (in dollars per share)	$ 0.93
$1.45 – $1.96
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Range of price, lower range limit (in dollars per share)	1.45
Range of price, upper range limit (in dollars per share)	$ 1.96
Number of Options, Outstanding and Exercisable (in shares)	109
Weighted Average Remaining Contractual Life (In Years)	4 years 11 months 1 day
Weighted Average Exercise Price, Outstanding and Exercisable (in dollars per share)	$ 1.54
$1.97 – $2.04
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Range of price, lower range limit (in dollars per share)	1.97
Range of price, upper range limit (in dollars per share)	$ 2.04
Number of Options, Outstanding and Exercisable (in shares)	881
Weighted Average Remaining Contractual Life (In Years)	5 years 4 days
Weighted Average Exercise Price, Outstanding and Exercisable (in dollars per share)	$ 1.98
$2.05 – $2.60
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Range of price, lower range limit (in dollars per share)	2.05
Range of price, upper range limit (in dollars per share)	$ 2.60
Number of Options, Outstanding and Exercisable (in shares)	55
Weighted Average Remaining Contractual Life (In Years)	4 years 22 days
Weighted Average Exercise Price, Outstanding and Exercisable (in dollars per share)	$ 2.20
$2.61 – $3.02
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Range of price, lower range limit (in dollars per share)	2.61
Range of price, upper range limit (in dollars per share)	$ 3.02
Number of Options, Outstanding and Exercisable (in shares)	101
Weighted Average Remaining Contractual Life (In Years)	4 years 2 months 5 days
Weighted Average Exercise Price, Outstanding and Exercisable (in dollars per share)	$ 3.02