Basic and Diluted Net Income (Loss) Per Share (Parenthetical) (Detail)	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Schedule of Earnings Per Share, Basic and Diluted, by Common Class [Line Items]
Antidilutive securities excluded from computation of earning per share	5,858,000	7,285,000	6,359,000