Fair Value of Financial Instruments - Change in Value of Warrant and Derivative Liability Unobservable Inputs Financial Instrument Reconciliation (Detail) (USD $)	9 Months Ended		9 Months Ended		9 Months Ended
	Sep. 30, 2014	Sep. 30, 2014 Senior Subordinated Notes Level 2	Sep. 30, 2014 Senior Subordinated Notes 2018 Notes	Dec. 31, 2013 Senior Subordinated Notes 2018 Notes Level 2	Sep. 30, 2014 Derivative Liability	Sep. 30, 2014 Warrant Liability
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair value, beginning balance	$ 6,602,000
Fair value of derivative liability for 2019 Notes recorded on measurement date	3,903,000
Change in fair value recorded as a loss from change in fair value of financial liability			(4,100,000)		(7,154,000)	(688,000)
Adjustment to fair value of derivative liability related to early conversion of the 2018 Notes			(1,000,000)		(1,003,000)
Fair value, ending balance	1,660,000
Fair value of Notes		$ 225,500,000		$ 117,700,000