Stockholders' Equity - Stock Options Additional Disclosures (Details) shares in Thousands	12 Months Ended
	Dec. 31, 2016 $ / shares shares
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range
Options Outstanding, Number of Shares | shares	5,687
Options Outstanding, Weighted Average Remaining Contractual Term	2 years 10 months 25 days
Options Outstanding, Weighted Average Exercise Price	$ 7.78
Options Exercisable, Number of Shares | shares	4,433
Options Exercisable, Weighted Average Exercise Price	$ 6.05
Exercise Price Range 0.29 - 0.33
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range
Exercise Price, minimum	0.29
Exercise Price, maximum	$ 0.33
Options Outstanding, Number of Shares | shares	729
Options Outstanding, Weighted Average Remaining Contractual Term	4 months 24 days
Options Outstanding, Weighted Average Exercise Price	$ 0.32
Options Exercisable, Number of Shares | shares	729
Options Exercisable, Weighted Average Exercise Price	$ 0.32
Exercise Price Range 1.85
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range
Exercise Price, maximum	$ 1.85
Options Outstanding, Number of Shares | shares	526
Options Outstanding, Weighted Average Remaining Contractual Term	2 years
Options Outstanding, Weighted Average Exercise Price	$ 1.85
Options Exercisable, Number of Shares | shares	526
Options Exercisable, Weighted Average Exercise Price	$ 1.85
Exercise Price Range 2.95
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range
Exercise Price, maximum	$ 2.95
Options Outstanding, Number of Shares | shares	1,147
Options Outstanding, Weighted Average Remaining Contractual Term	2 years 7 months 6 days
Options Outstanding, Weighted Average Exercise Price	$ 2.95
Options Exercisable, Number of Shares | shares	1,147
Options Exercisable, Weighted Average Exercise Price	$ 2.95
Exercise Price Range 10.39
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range
Exercise Price, maximum	$ 10.39
Options Outstanding, Number of Shares | shares	2,085
Options Outstanding, Weighted Average Remaining Contractual Term	3 years 7 months 6 days
Options Outstanding, Weighted Average Exercise Price	$ 10.39
Options Exercisable, Number of Shares | shares	1,793
Options Exercisable, Weighted Average Exercise Price	$ 10.39
Exercise Price Range 15.00
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range
Exercise Price, maximum	$ 15.00
Options Outstanding, Number of Shares | shares	1,200
Options Outstanding, Weighted Average Remaining Contractual Term	3 years 9 months 18 days
Options Outstanding, Weighted Average Exercise Price	$ 15.00
Options Exercisable, Number of Shares | shares	238
Options Exercisable, Weighted Average Exercise Price	$ 15.00