Net Income (Loss) Per Share - Net Income (Loss) Per Share (Detail) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013
Numerator:
Net loss available to common stockholders	$ (5,695)	$ (7,244)	$ (10,862)	$ (13,402)
Denominator:
Weighted average shares outstanding - basic	38,518	37,247	38,118	36,932
Potential common shares - options (treasury stock method)
Weighted average shares outstanding - diluted	38,518	37,247	38,118	36,932
Shares excluded (anti-dilutive)	11		86	8
Shares excluded due to an exercise price greater than weighted average stock price for the period	2,090	2,323	1,347	1,457
Net loss per common share:
Basic	$ (0.15)	$ (0.19)	$ (0.28)	$ (0.36)
Diluted	$ (0.15)	$ (0.19)	$ (0.28)	$ (0.36)