Stockholders' Equity-Common and Preferred Shares - Summary of Company's Outstanding Common Stock Warrants (Detail) In Thousands, unless otherwise specified	Sep. 30, 2013	Sep. 23, 2013	Dec. 31, 2012
Class of Warrant or Right [Line Items]
Exercise Price	2.24	2.80
Total Number of Warrants Outstanding	5,313		13
Committed Equity Financing Facility [Member]
Class of Warrant or Right [Line Items]
Date of Issuance	Feb. 19, 2008
Exercise Price	657.60
Total Number of Warrants Outstanding			1
Direct Registration Series I Warrants [Member]
Class of Warrant or Right [Line Items]
Date of Issuance	Jul. 20, 2009
Exercise Price	504.00
Total Number of Warrants Outstanding	12		12
Private Placement Series A Warrants [Member]
Class of Warrant or Right [Line Items]
Date of Issuance	Apr. 16, 2013
Exercise Price	3.40
Total Number of Warrants Outstanding	1,460
Private Placement Series B Warrants [Member]
Class of Warrant or Right [Line Items]
Date of Issuance	Apr. 16, 2013
Exercise Price	3.40
Total Number of Warrants Outstanding	1,242
Private Placement Warrants [Member]
Class of Warrant or Right [Line Items]
Date of Issuance	Sep. 23, 2013
Exercise Price	2.24
Total Number of Warrants Outstanding	2,452
Private Placement Warrants One [Member]
Class of Warrant or Right [Line Items]
Date of Issuance	Sep. 23, 2013
Exercise Price	2.80
Total Number of Warrants Outstanding	147