Stock Option and Other Benefit Plans - Additional Information (Detail) (USD $) In Thousands, except Per Share data, unless otherwise specified	12 Months Ended												12 Months Ended		1 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2012 Incentive Stock Option	Dec. 31, 2012 Incentive Stock Option Minimum	Dec. 31, 2012 Nonqualified Stock Options	Dec. 31, 2012 Nonqualified Stock Options Minimum	Dec. 31, 2012 Stock Options Granted Prior To October Twenty Five, Two Thousand Seven	Dec. 31, 2012 Stock Options Granted After To October Twenty Five Two Thousand Seven	Dec. 31, 2012 2007 Equity Incentive Plan	Jan. 31, 2007 2007 Equity Incentive Plan	Dec. 31, 2012 2007 Equity Incentive Plan Previously Authorized but Unissued	Dec. 31, 2012 2007 Employee Stock Purchase Plan	Jan. 31, 2007 2007 Employee Stock Purchase Plan	Jan. 31, 2009 2007 Employee Stock Purchase Plan Offering period that commenced on February 15, 2009 and ended on August 14, 2009	Jan. 31, 2009 2007 Employee Stock Purchase Plan Offering period thereafter	Oct. 31, 2011 2007 Employee Stock Purchase Plan Offering period that commenced on August 22, 2011 and for each offering period thereafter	Nov. 30, 2012 2008 Equity Inducement Plan	Aug. 31, 2011 2008 Equity Inducement Plan	Jan. 31, 2010 2008 Equity Inducement Plan	Dec. 31, 2012 2008 Equity Inducement Plan	Mar. 31, 2008 2008 Equity Inducement Plan Minimum	Jan. 31, 2010 2008 Equity Inducement Plan Maximum	Dec. 31, 2012 Inducement Incentive Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares available for grants										740	1,766	195	786	667								600	1,250	438
Common stock authorized for issuance, increased										3,000								300	1,050	819
Number of shares of common stock outstanding increase percentage										3.00%
Exercise price of options percentage of fair market value of common stock on grant date					100.00%		85.00%
Exercise price minimum percentage for option granted to 10% of stockholder				110.00%		110.00%
Stock options granted to employees vesting percentage	25.00%
Stock options granted to employees vesting period	1 year
Stock option granted contractual term								10 years	6 years
Percentage of outstanding shares reserved for grant increase during each January 1 for the first eight calendar years													1.00%
Maximum amount of shares that may be issued over the term of the plan													5,333
Maximum Offering Period Share Amount															500	200	300
Exercise price of non qualified stock options as percent of fair market value of company's common stock, minimum																					100.00%
Quoted closing price of Company's common stock	$ 2.28
Total intrinsic value of awards exercised	$ 2,114	$ 2,065	$ 142
Weighted-average fair value of stock options granted	$ 1.90	$ 1.81	$ 0.67
Stock-based compensation contingent consideration at fair value (includes unvested portion of the liability)	2,242	1,176
Stock-based compensation expense recorded as contingent liability	1,549	551
Cash prodceed from option exercise, net	1,357	1,633	287
Income tax benefit from stock option exercises	0	0	0
Unrecognized compensation expense	$ 7,300
Unrecognized compensation expense recognized over weighted average period	2 years 8 months 23 days