Stock-Based Compensation (Detail) - Summary of Stock Options Activity (USD $) In Thousands, except Share data, unless otherwise specified	3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012
Awards outstanding, December 31, 2012	3,251,849
Awards outstanding, December 31, 2012 (in Dollars per share)	$ 2.22
Options granted	409,500	1,953,500
Options granted (in Dollars per share)	$ 1.83
Options cancelled	(67,050)
Options cancelled (in Dollars per share)	$ 3.02
Options expired	(41,152)
Options expired (in Dollars per share)	$ 4.66
Awards outstanding, March 31, 2013	3,553,147
Awards outstanding, March 31, 2013 (in Dollars per share)	$ 2.13
Awards outstanding, March 31, 2013	4 years 357 days
Awards outstanding, March 31, 2013 (in Dollars)	$ 576
Awards vested and expected to vest at March 31, 2013	3,163,760
Awards vested and expected to vest at March 31, 2013 (in Dollars per share)	$ 2.18
Awards vested and expected to vest at March 31, 2013	4 years 332 days
Awards vested and expected to vest at March 31, 2013 (in Dollars)	501
Awards exercisable at March 31, 2013	875,182
Awards exercisable at March 31, 2013 (in Dollars per share)	$ 3.34
Awards exercisable at March 31, 2013	3 years 219 days
Awards exercisable at March 31, 2013 (in Dollars)	$ 55