Computation of Basic and Diluted Earnings per Share (Detail) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2012	Jun. 30, 2011	Jun. 30, 2012	Jun. 30, 2011
Net loss	$ (93,649)	$ (3,333)	$ (33,465)	$ (5,367)
Weighted average shares of common stock outstanding (used to calculate basic EPS)	76,210	72,479	74,547	71,846
Net effect of dilutive employee stock options based on the treasury stock method	234	116	226	129
Weighted average shares of common stock outstanding (used to calculate diluted EPS)	76,444	72,595	74,773	71,975
Net income / (loss) per common share - basic	$ (1.23)	$ (0.05)	$ (0.45)	$ (0.07)
Net income / (loss) per common share - diluted	$ (1.23)	$ (0.05)	$ (0.45)	$ (0.07)