Stockholders' Equity-Common and Preferred Shares - Summary of Factors Used to Determine the Value of Outstanding Series A and C Warrants /Summary of Fair Value of CEFF Warrants Valuation/ the Fair Value of the Direct Registration Warrants Valuation (Detail) (USD $) In Thousands, except Per Share data, unless otherwise specified			1 Months Ended	12 Months Ended	1 Months Ended	12 Months Ended	1 Months Ended	12 Months Ended
	Jan. 19, 2011	Dec. 31, 2010	Jan. 19, 2011 Committed Equity Financing Facility [Member]	Dec. 31, 2010 Committed Equity Financing Facility [Member]	Jan. 19, 2011 Series A [Member]	Dec. 31, 2010 Series A [Member]	Jan. 19, 2011 Series C [Member]	Dec. 31, 2010 Series C [Member]	Dec. 31, 2013 Direct Registration Series I Warrants [Member]	Dec. 31, 2012 Direct Registration Series I Warrants [Member]	Dec. 31, 2011 Direct Registration Series I Warrants [Member]
Class of Warrant or Right [Line Items]
Stock Price			$ 51.84	$ 55.20	$ 51.84	$ 55.20	$ 51.84	$ 55.20	$ 2.52	$ 5.35	$ 11.88
Exercise Price			$ 658	$ 658	$ 67.20	$ 67.20	$ 67.20	$ 67.20	$ 504	$ 504	$ 504
Contractual life (in Years)			2 years 7 months 6 days	2 years 7 months 6 days	4 years 1 month 6 days	4 years 2 months 12 days	4 years 6 months	4 years 6 months	7 months 6 days	1 year 7 months 6 days	2 years 7 months 6 days
Expected volatility			87.00%	96.00%	82.00%	81.00%	79.00%	80.00%	91.00%	101.00%	107.00%
Risk-free interest rate			0.82%	1.02%	1.53%	2.01%	1.68%	2.01%	0.13%	0.25%	0.36%
Fair market value	$ 6,633	$ 7,498	$ 3	$ 6	$ 3,663	$ 4,143	$ 2,970	$ 3,355	$ 0	$ 0	$ 6