Additional Information About Stock Options Outstanding and Exercisable (Detail) (USD $)	6 Months Ended
	Jun. 30, 2013
Range 1
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Lower Limit	$ 1.19
Upper Limit	$ 2.51
Options Outstanding, Number of Shares	1,795,502
Options Outstanding, Weighted Average Remaining Contractual Life	6 years 9 months 18 days
Options Outstanding, Weighted Average Exercise Price	$ 1.83
Options Exercisable, Number of Shares	1,201,560
Options Exercisable, Wtd. Average Exercise Price	$ 1.80
Range 2
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Lower Limit	$ 3.05
Upper Limit	$ 3.57
Options Outstanding, Number of Shares	66,300
Options Outstanding, Weighted Average Remaining Contractual Life	1 year 6 months
Options Outstanding, Weighted Average Exercise Price	$ 3.52
Options Exercisable, Number of Shares	66,300
Options Exercisable, Wtd. Average Exercise Price	$ 3.52
Range 3
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Lower Limit	$ 3.69
Upper Limit	$ 4.65
Options Outstanding, Number of Shares	218,612
Options Outstanding, Weighted Average Remaining Contractual Life	4 years 2 months 12 days
Options Outstanding, Weighted Average Exercise Price	$ 4.19
Options Exercisable, Number of Shares	218,612
Options Exercisable, Wtd. Average Exercise Price	$ 4.19
Range 4
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Lower Limit	$ 1.19
Upper Limit	$ 4.65
Options Outstanding, Number of Shares	2,080,414
Options Outstanding, Weighted Average Remaining Contractual Life	6 years 4 months 24 days
Options Outstanding, Weighted Average Exercise Price	$ 2.13
Options Exercisable, Number of Shares	1,486,472
Options Exercisable, Wtd. Average Exercise Price	$ 2.22