Stock-Based Compensation and Stock Purchase Plans - Summary of Unvested Stock Option Awards (Detail) (Options [Member], USD $)	12 Months Ended
	Dec. 31, 2013
Options [Member]
Summary of unvested stock option awards
Unvested Outstanding, shares, beginning balance	1,380,000
Outstanding Granted, shares	920,000
Outstanding Vested, shares	(452,000)
Outstanding Forfeited, shares	(20,000)
Unvested Outstanding, shares, ending balance	1,828,000
Unvested Outstanding, Weighted-Average Grant - Date Fair Value, beginning balance	$ 4.88
Granted, Weighted-Average Grant - Date Fair Value	$ 3.06
Vested, Weighted-Average Grant - Date Fair Value	$ (4.27)
Forfeited, Weighted-Average Grant - Date Fair Value	$ (3.04)
Unvested Outstanding, Weighted-Average Grant - Date Fair Value, ending balance	$ 4.14