Stock Based Compensation (Details) (USD $)	3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Reverse stock split conversation ratio	1-for-7
Share-based compensation arrangement by share-based payment award, fair value assumptions and methodology [Abstract]
Unrecognized compensation cost, recognized as expense over a weighted-average period	1 year 3 months
Employees [Member]
Share-based compensation arrangement by share-based payment award, fair value assumptions and methodology [Abstract]
Estimated annualized forfeiture rate (in hundredths)	12.00%	14.00%
Senior management [Member]
Share-based compensation arrangement by share-based payment award, fair value assumptions and methodology [Abstract]
Estimated annualized forfeiture rate (in hundredths)	3.00%	2.00%
Directors and nonemployees [Member]
Share-based compensation arrangement by share-based payment award, fair value assumptions and methodology [Abstract]
Estimated annualized forfeiture rate (in hundredths)	0.00%	0.00%
Employees and Directors [Member]
Share-based compensation arrangement by share-based payment award, fair value assumptions and methodology [Abstract]
Unrecognized compensation expense related to unvested stock options, granted	1,600,000
Stock Options [Member]
Share-based compensation arrangement by share-based payment award, fair value assumptions and methodology [Abstract]
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Method Used	Black-Scholes option-pricing model
Risk-free interest rate (in hundredths)	1.16%
Expected volatility, Minimum (in hundredths)	85.40%
Expected volatility, Maximum (in hundredths)	85.80%
Expected lives	6 years
Expected dividend yield (in hundredths)	0.00%
Number of Options (Employees and Non-Employees) [Abstract]
Outstanding at beginning of period (in shares)	3,382,993
Granted (in shares)	89,176
Forfeited or expired (in shares)	(103,716)
Outstanding at end of period (in shares)	3,368,453
Options exercisable at end of period (in shares)	2,153,911
Weighted-Average Exercise Price Options [Abstract]
Outstanding at beginning of period (in dollars per share)	4.17
Granted (in dollars per share)	2.45
Forfeited or expired (in dollars per share)	3.08
Outstanding at end of period (in dollars per share)	4.16
Options exercisable at end of period (in dollars per share)	5.28
Number of Unvested Stock Options (Employees and Non-Employees) [Abstract]
Non-vested at beginning of period (in shares)	1,331,318
Granted, unvested stock options (in shares)	89,176
Forfeited or expired, unvested stock options (in shares)	(103,716)
Vested (in shares)	(102,236)
Non-vested at end of period (in shares)	1,214,542
Weighted average grant date fair value per share [Abstract]
Non-vested at beginning of period (in dollars per share)	1.69
Granted, unvested stock options (in dollars per share)	1.75
Forfeited or expired, unvested stock options (in dollars per share)	2.32
Vested (in dollars per share)	1.90
Non-vested at end of period (in dollars per share)	1.69
Total stock-based compensation expense resulting from stock options and warrants [Abstract]
Share-based compensation arrangement by share-based payment award, shares issued in period (in shares)	89,176
Share based compensation, shares authorized under significant ranges of outstanding stock option plans in period [Abstract]
Number of Options (in shares)	3,368,453
Weighted-Average Remaining Contractual Life	7 years 5 months 27 days
Weighted-Average Exercise Price (in dollars per share)	4.16
Number of Options Exercisable (in shares)	2,153,911
Weighted-Average Contractual Life	7 years 5 months 27 days
Weighted-Average Exercise Price, Options Exercisable (in dollars per share)	5.28
The aggregate intrinsic value of outstanding options	4,000,000
Closing price of the common stock (in dollars per share)	2.72
Stock Options [Member] | Range $ 1.83 - 3.00 [Member]
Share based compensation, shares authorized under significant ranges of outstanding stock option plans in period [Abstract]
Range of Exercise Prices, Lower Range (in dollars per share)	1.83
Range of Exercise Prices, Upper Range (in dollars per share)	3.00
Number of Options (in shares)	2,115,545
Weighted-Average Remaining Contractual Life	9 years 3 months 4 days
Weighted-Average Exercise Price (in dollars per share)	1.98
Number of Options Exercisable (in shares)	962,073
Weighted-Average Contractual Life	9 years 3 months 4 days
Weighted-Average Exercise Price, Options Exercisable (in dollars per share)	2.03
Stock Options [Member] | Range $ 3.01 - 7.00 [Member]
Share based compensation, shares authorized under significant ranges of outstanding stock option plans in period [Abstract]
Range of Exercise Prices, Lower Range (in dollars per share)	3.01
Range of Exercise Prices, Upper Range (in dollars per share)	7.00
Number of Options (in shares)	178,512
Weighted-Average Remaining Contractual Life	5 years 7 days
Weighted-Average Exercise Price (in dollars per share)	5.24
Number of Options Exercisable (in shares)	174,869
Weighted-Average Contractual Life	5 years 7 days
Weighted-Average Exercise Price, Options Exercisable (in dollars per share)	5.27
Stock Options [Member] | Range $ 7.01 - 8.50 [Member]
Share based compensation, shares authorized under significant ranges of outstanding stock option plans in period [Abstract]
Range of Exercise Prices, Lower Range (in dollars per share)	7.01
Range of Exercise Prices, Upper Range (in dollars per share)	8.50
Number of Options (in shares)	942,110
Weighted-Average Remaining Contractual Life	4 years 10 months 17 days
Weighted-Average Exercise Price (in dollars per share)	7.66
Number of Options Exercisable (in shares)	884,683
Weighted-Average Contractual Life	4 years 10 months 17 days
Weighted-Average Exercise Price, Options Exercisable (in dollars per share)	7.69
Stock Options [Member] | Range $ 8.51 - 32.55 [Member]
Share based compensation, shares authorized under significant ranges of outstanding stock option plans in period [Abstract]
Range of Exercise Prices, Lower Range (in dollars per share)	8.51
Range of Exercise Prices, Upper Range (in dollars per share)	32.55
Number of Options (in shares)	132,286
Weighted-Average Remaining Contractual Life	1 year 6 months 29 days
Weighted-Average Exercise Price (in dollars per share)	12.75
Number of Options Exercisable (in shares)	132,286
Weighted-Average Contractual Life	1 year 6 months 29 days
Weighted-Average Exercise Price, Options Exercisable (in dollars per share)	12.75
Stock Options [Member] | Maximum [Member]
Share-based compensation arrangement by share-based payment award, fair value assumptions and methodology [Abstract]
Expected lives	10 years
Stock Options [Member] | Employees [Member]
Number of Options (Employees and Non-Employees) [Abstract]
Outstanding at beginning of period (in shares)	3,240,850
Granted (in shares)	89,176
Forfeited or expired (in shares)	(103,716)
Outstanding at end of period (in shares)	3,226,310
Options exercisable at end of period (in shares)	2,020,696
Number of Unvested Stock Options (Employees and Non-Employees) [Abstract]
Non-vested at beginning of period (in shares)	1,322,389
Granted, unvested stock options (in shares)	89,176
Forfeited or expired, unvested stock options (in shares)	(103,716)
Vested (in shares)	(102,236)
Non-vested at end of period (in shares)	1,205,613
Stock Options [Member] | Non employees [Member]
Number of Options (Employees and Non-Employees) [Abstract]
Outstanding at beginning of period (in shares)	142,143
Granted (in shares)	0
Forfeited or expired (in shares)	0
Outstanding at end of period (in shares)	142,143
Options exercisable at end of period (in shares)	133,215
Number of Unvested Stock Options (Employees and Non-Employees) [Abstract]
Non-vested at beginning of period (in shares)	8,929
Granted, unvested stock options (in shares)	0
Forfeited or expired, unvested stock options (in shares)	0
Vested (in shares)	0
Non-vested at end of period (in shares)	8,929
Stock Options And Warrants [Member] | Employees [Member]
Total stock-based compensation expense resulting from stock options and warrants [Abstract]
Allocated employee and non-employee stock-based compensation expense, Total	234,812	269,196
Stock Options And Warrants [Member] | Non-Employees [Member]
Total stock-based compensation expense resulting from stock options and warrants [Abstract]
Allocated employee and non-employee stock-based compensation expense, Total	27,212	52,418
Stock Options And Warrants [Member] | Research and Development Expense [Member] | Employees [Member]
Total stock-based compensation expense resulting from stock options and warrants [Abstract]
Allocated employee and non-employee stock-based compensation expense, Total	50,172	95,124
Stock Options And Warrants [Member] | Research and Development Expense [Member] | Non-Employees [Member]
Total stock-based compensation expense resulting from stock options and warrants [Abstract]
Allocated employee and non-employee stock-based compensation expense, Total	0	0
Stock Options And Warrants [Member] | General and Administrative Expense [Member] | Employees [Member]
Total stock-based compensation expense resulting from stock options and warrants [Abstract]
Allocated employee and non-employee stock-based compensation expense, Total	184,640	174,072
Stock Options And Warrants [Member] | General and Administrative Expense [Member] | Non-Employees [Member]
Total stock-based compensation expense resulting from stock options and warrants [Abstract]
Allocated employee and non-employee stock-based compensation expense, Total	27,212	52,418
Restricted Stock [Member]
Number of Unvested Stock Options (Employees and Non-Employees) [Abstract]
Granted, unvested stock options (in shares)	100,000
Total stock-based compensation expense resulting from stock options and warrants [Abstract]
Allocated employee and non-employee stock-based compensation expense, Total	45,984	0
Restricted Stock [Member] | Senior management [Member]
Number of Options (Employees and Non-Employees) [Abstract]
Outstanding at end of period (in shares)	100,000
2000 Long Term Incentive Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common stock reserved for future issuance (in shares)	1,400,000
Share-based compensation, shares subject to stock options (in shares)	1,000,000
Expiration date	Aug. 06, 2010
Share-based compensation, shares available for future grant (in shares)	0
2008 Stock Incentive Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common stock reserved for future issuance (in shares)	10,000,000
Share-based compensation, shares subject to stock options (in shares)	2,300,000
Share-based compensation, shares available for future grant (in shares)	2,700,000
2008 Stock Incentive Plan [Member] | Restricted Stock [Member] | Senior management [Member]
Weighted average grant date fair value per share [Abstract]
Expected to vest (in shares)	50,000
Expected to vest over subsequent period (in shares)	50,000
Value of restricted shares issued	186,900