Options Outstanding (Detail) (USD $)	6 Months Ended
	Jun. 30, 2012	Dec. 31, 2011
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total shares issuable upon exercise	6,186,261	5,886,261
Options exercisable	3,734,703
Options not vested	2,451,558
Total shares issuable upon exercise	$ 1.10	$ 1.11
Options exercisable	$ 1.05
Options not vested	$ 1.19
Total shares issuable upon exercise	3 years 4 months 24 days
Options exercisable	3 years 1 month 6 days
Options not vested	3 years 9 months 18 days
Total shares issuable upon exercise	$ 363,419
Options exercisable	106,229
Options not vested	$ 257,190