Business and Basis of Presentation - Restatement Corrections and Other Immaterial Adjustments on Condensed Consolidated Statements of Comprehensive (Loss) Income (Detail) (USD $)	3 Months Ended		6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012
As Reported [Member]
Net -loss) income	$ (10,177,000)	$ 18,070,000	$ (12,966,000)	$ 64,612,000
Total comprehensive -loss) income	(10,058,000)	17,704,000	(12,189,000)	64,314,000
As Restated [Member]
Net -loss) income	(9,721,000)	18,350,000	(15,157,000)	65,187,000
Total comprehensive -loss) income	$ (9,602,000)	$ 17,984,000	$ (14,380,000)	$ 64,889,000