Stock-Based Compensation (Details) (Service-based stock options, USD $)	3 Months Ended		12 Months Ended
	Mar. 31, 2013	Mar. 31, 2012	Dec. 31, 2012
Service-based stock options
Stock-Based Compensation
Vesting period	4 years
Expiration period	10 years
Weighted average grant-date fair value (in dollars per share)	$ 0.85	$ 1.22
Net compensation expense (income) related to employees and directors (in dollars)	$ (43,000)	$ 815,000
Forfeiture adjustment in compensation costs due to restructuring activities (in dollars)	938,000
Weighted average assumptions used to estimate fair value of each service-based stock option grant
Expected dividend rate (as a percent)	0.00%	0.00%
Expected stock price volatility (as a percent)	74.00%	73.90%
Risk-free interest rate (as a percent)	1.40%	1.40%
Expected life	6 years 3 months 18 days	6 years 3 months 18 days
Options
Outstanding at the beginning of the period (in shares)	9,987,468
Granted (in shares)	1,100,000
Outstanding at the end of the period (in shares)	11,087,468		9,987,468
Exercisable at the end of the period (in shares)	4,956,364
Weighted Average Exercise Price
Outstanding at the beginning of the period (in dollars per share)	$ 2.38
Granted (in dollars per share)	$ 1.29
Outstanding at the end of the period (in dollars per share)	$ 2.27		$ 2.38
Exercisable at the end of the period (in dollars per share)	$ 2.59
Weighted Average Remaining Contractual Term
Outstanding at the beginning of the period	7 years 4 months 24 days		7 years 6 months
Outstanding at the end of the period	7 years 4 months 24 days		7 years 6 months
Exercisable at the end of the period	5 years 6 months
Additional disclosures
Total unrecognized compensation cost (in dollars)	3,710,000
Weighted average period over which unrecognized compensation is expected to be recognized	3 years
Total fair value of options vested (in dollars)	$ 917,000	$ 836,000