Changes in Fair Value of Financial Liabilities Measured at Fair Value on Recurring Basis Using Significant Unobservable Inputs (Detail) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2012
Warrant Liability
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Valuation on May 9, 2012 (date of debt exchange transaction, see Note 7)	$ 5,282
Unrealized gain	2,347
Balance at December 31, 2012	2,935
Debt Redemption Features
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Valuation on May 9, 2012 (date of debt exchange transaction, see Note 7)	948
Unrealized gain	100
Balance at December 31, 2012	$ 848