Basic And Diluted Loss Per Share (Detail) (USD $) In Thousands, except Share data, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2012	Jun. 30, 2011	Jun. 30, 2012	Jun. 30, 2011
Basic and Diluted Earnings (Loss) Per Common Share:
Net income (loss)	$ 10,638	$ (27,980)	$ 12,903	$ (47,859)
Less: distributed and undistributed earnings allocated to participating securities	(149)	(206)	(308)	(365)
Earnings (loss) attributable to common stockholders	$ 10,489	$ (28,186)	$ 12,595	$ (48,224)
Basic weighted-average shares outstanding	47,398,088	46,719,233	47,367,051	46,717,408
Dilutive effect of common stock equivalents	354,641		310,016
Diluted weighted-average common shares outstanding, assuming conversion of common stock equivalents	47,752,729	46,719,233	47,677,067	46,717,408
Basic Earnings (Loss) Per Common Share	$ 0.22	$ (0.60)	$ 0.27	$ (1.03)
Diluted	$ 0.22	$ (0.60)	$ 0.26	$ (1.03)