Summary of Options Outstanding and Exercisable (Detail) (USD $)	Dec. 31, 2012
$0.88 to $ 4.99
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Exercise Price Minimum	$ 0.88
Exercise Price Maximum	$ 4.99
Weighted Average Remaining Contractual Life (years)	5 years 10 months 2 days
Number of Options Outstanding	599,706
Number of Options Exercisable	258,337
$5.00 to $9.99
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Exercise Price Minimum	$ 5.00
Exercise Price Maximum	$ 9.99
Weighted Average Remaining Contractual Life (years)	1 year 6 months 29 days
Number of Options Outstanding	178,054
Number of Options Exercisable	157,221
$10.00 to $39.20
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Exercise Price Minimum	$ 10.00
Exercise Price Maximum	$ 39.20
Weighted Average Remaining Contractual Life (years)	2 months 16 days
Number of Options Outstanding	46,860
Number of Options Exercisable	46,860
$0.88 to $39.20
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Exercise Price Minimum	$ 0.88
Exercise Price Maximum	$ 39.20
Weighted Average Remaining Contractual Life (years)	7 years 7 months 17 days
Number of Options Outstanding	824,620
Number of Options Exercisable	462,418