Supplemental Cash Flow Information - Summary of Additional Cash Flow Information (Detail) (USD $) In Thousands, unless otherwise specified	6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012
Supplemental disclosures of cash flow information:
Cash paid for interest		$ 1,161
Non-cash investing and financing activities:
Accrued preferred stock dividend		115
Accrued warrant liability		10,399
Accrued derivative liability		1,207
Subscription receivable		550
Conversion of preferred stock derivative balance into common stock		80
Cashless exercise of warrants recorded as a liability	(38)
Common stock issued in connection with conversion of debt		$ 25