Common Shares Underlying Stock Options Convertible Preferred Stock Employee Stock Purchase Plan Rights Warrants and Restricted Stock Units Excluded from Calculation of Weighted Average Number of Common Shares Outstanding used for Calculation of Diluted Net Income Loss Per Common Share (Detail) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Weighted average of anti-dilutive potential common shares	8,716	13,595	9,867