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, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012
Numerator:
Net loss available to common stockholders	$ (7,244)	$ (6,825)	$ (13,402)	$ (16,507)
Denominator:
Weighted average shares outstanding - basic	37,247	36,045	36,932	35,818
Potential common shares - options (treasury stock method)
Weighted average shares outstanding - diluted	37,247	36,045	36,932	35,818
Shares excluded (anti-dilutive)		18	8	25
Shares excluded due to an exercise price greater than weighted average stock price for the period	2,323	1,483	1,457	1,364
Net loss per common share:
Basic	$ (0.19)	$ (0.19)	$ (0.36)	$ (0.46)
Diluted	$ (0.19)	$ (0.19)	$ (0.36)	$ (0.46)