Calculation of Net Income (Loss) and the Number of Shares Used to Compute Basic and Diluted Earnings per Share (Detail) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Earnings Per Share, Diluted, by Common Class, Including Two Class Method [Line Items]
Net income (loss)	$ (123,603)	$ 85,248	$ (80,008)
Weighted average shares outstanding - basic	132,375	113,020	93,330
Dilutive stock options		572
Restricted stock and restricted stock units		1,142
Weighted average shares outstanding -- diluted	132,375	114,734	93,330