Organization, Basis of Presentation and Summary of Significant Accounting Policies - Net Income (Loss) Per Share (Detail) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Numerator:
Net loss available to common stockholders	$ (1,502)	$ (13,049)	$ (7,244)	$ (6,158)	$ (4,143)	$ (4,813)	$ (6,825)	$ (9,682)	$ (27,953)	$ (25,463)	$ (159,606)
Denominator:
Weighted average shares outstanding - basic	37,027	37,036	37,247	36,614	35,882	35,879	36,045	35,590	36,982	35,849	35,617
Potential common shares - options (treasury stock method)
Weighted average shares outstanding - diluted	37,027	37,036	37,247	36,614	35,882	35,879	36,045	35,590	36,982	35,849	35,617
Shares excluded (anti-dilutive)									2	174	126
Shares excluded due to an exercise price greater than weighted average stock price for the period									2,150	1,453	1,561
Net loss per common share:
Basic	$ (0.04)	$ (0.35)	$ (0.19)	$ (0.17)	$ (0.12)	$ (0.13)	$ (0.19)	$ (0.27)	$ (0.76)	$ (0.71)	$ (4.48)
Diluted	$ (0.04)	$ (0.35)	$ (0.19)	$ (0.17)	$ (0.12)	$ (0.13)	$ (0.19)	$ (0.27)	$ (0.76)	$ (0.71)	$ (4.48)