Stock Benefit Plans and Stock-Based Compensation - Additional Information (Detail) (USD $)	0 Months Ended	1 Months Ended	12 Months Ended				1 Months Ended	12 Months Ended									1 Months Ended	12 Months Ended										12 Months Ended				1 Months Ended
	Nov. 19, 2012 Quarter	Dec. 19, 2012	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011	Mar. 31, 2012	May 31, 2013 Media Advertising Agreement [Member]	Dec. 31, 2013 Media Advertising Agreement [Member]	Dec. 31, 2012 Media Advertising Agreement [Member]	Dec. 31, 2013 Maximum [Member]	Dec. 31, 2012 Maximum [Member]	Dec. 31, 2011 Maximum [Member]	Dec. 31, 2013 Minimum [Member]	Dec. 31, 2012 Minimum [Member]	Dec. 31, 2011 Minimum [Member]	Nov. 19, 2012 Minimum [Member]	Dec. 31, 2011 Warrants [Member]	Dec. 31, 2013 Warrants [Member]	Dec. 31, 2013 Stock options [Member]	Dec. 31, 2012 Stock options [Member]	Dec. 31, 2011 Stock options [Member]	Dec. 31, 2013 Restricted Stock Awards [Member]	Dec. 31, 2012 Restricted Stock Awards [Member]	Dec. 31, 2011 Restricted Stock Awards [Member]	May 31, 2013 Registered shares [Member] Media Advertising Agreement [Member]	Dec. 31, 2012 Registered shares [Member] Media Advertising Agreement [Member]	Dec. 31, 2012 Unregistered shares [Member] Media Advertising Agreement [Member]	Dec. 31, 2013 2005 Plan [Member]	Dec. 31, 2013 2005 Plan [Member] Maximum [Member]	Dec. 31, 2013 2005 Plan [Member] Minimum [Member]	Dec. 31, 2013 2005 Plan [Member] Incentive stock options [Member]	Oct. 31, 2013 Collaborative Arrangement [Member] payment	Dec. 31, 2013 Collaborative Arrangement [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common stock reserved for issuance			12,377,000																									14,200,000
Options granted expiration term																													10 years		5 years
Stock options voting rights, percentage (more than 10%)																														10.00%
Share based payment award options, vesting period																															4 years
Exercise price of incentive stock options, percent (less than 100%)																												100.00%
Exercise price of option granted to stock holder, percent																												10.00%
Exercise price of stock options granted to 10 percent stockholder , percent																												110.00%
Shares of common stock remained available for issuance																												3,200,000
Weighted-average grant-date fair value of stock options granted																			$ 1.09	$ 1.10	$ 1.48
Closing stock price																			$ 2.01
Unrecognized compensation expense for stock options and awards expected to be recognized																			$ 3,300,000
Straight-line basis over a weighted average period																			2 years 8 months 12 days
Total intrinsic value of options exercised																					100,000
Stock options exercise price	$ 2.00	$ 2.05														$ 2.85
Stock options exercise price percentage	115.00%
Exchanged options issued to optionees for a reduced number of options		1,109,604
Exchanged option vesting period	3 years
Percentage of award vesting on the first anniversary	33.33%
Number of quarterly vesting installments	8
Weighted average fair value of awards granted																						$ 1.97	$ 1.57	$ 2.61
Purchase of common stock shares for issuance of warrants						500,000											93,750
Exercise price of warrants						2.50											1.60
Warrants expiration date			March 1, 2015
Vesting percentage of warrants			100.00%
Credit facility, finance charges																	200,000
Term of warrants																	10 years
Value of warrants																		100,000
Warrants risk free interest rate																		1.23%
Warrants volatility																		57.40%
Warrants expected term										5 years 6 months	5 years 9 months 18 days	5 years 10 months 24 days	5 years 3 months 18 days	5 years 3 months 18 days	5 years 9 months 18 days			10 years
Collaborative arrangement term																																3 years
Collaborative arrangement, number of periodic payment																																3
Collaborative arrangement, periodic payment aggregate amount																																8,000,000
Collaborative payments, per share price																																$ 1.95
Number of days leading up to and including date of signing collaboration agreement for per share price used to calculate annual payments to collaborator																																5 days
Number of months of services provided for number of shares issued used to calculate annual payments to collaborator																																12 months
Consulting fees paid							200,000		200,000
Common stock issued			97,599,000	96,703,000																					225,000	500,000	352,000						128,571
Stock based compensation			$ 4,078,000	$ 3,690,000	$ 2,425,000			$ 700,000	$ 1,100,000