Stockholders' Equity - Common and Preferred Shares - Summary of Company's Outstanding Common Stock Warrants (Detail) (USD $) In Thousands, except Per Share data, unless otherwise specified					9 Months Ended		9 Months Ended			9 Months Ended			9 Months Ended		9 Months Ended		9 Months Ended
	Sep. 30, 2014	May 28, 2014	Feb. 18, 2014	Dec. 31, 2013	Sep. 30, 2014 Direct Registration Series I Warrants [Member]	Dec. 31, 2013 Direct Registration Series I Warrants [Member]	Sep. 30, 2014 Private Placement Series A Warrants [Member]	Dec. 31, 2013 Private Placement Series A Warrants [Member]	Apr. 16, 2013 Private Placement Series A Warrants [Member]	Sep. 30, 2014 Private Placement Series B Warrants [Member]	Dec. 31, 2013 Private Placement Series B Warrants [Member]	Apr. 16, 2013 Private Placement Series B Warrants [Member]	Sep. 30, 2014 Private Placement Warrants [Member]	Dec. 31, 2013 Private Placement Warrants [Member]	Sep. 30, 2014 Private Placement Warrants One [Member]	Dec. 31, 2013 Private Placement Warrants One [Member]	Sep. 30, 2014 Public Offering Warrants [Member]	Sep. 30, 2014 Public Offering Warrants One [Member]	Sep. 30, 2014 Private Placement Warrants Two [Member]	Sep. 30, 2014 Private Placement Warrants Three [Member]
Class of Warrant or Right [Line Items]
Date of Issuance					Jul. 20, 2009		Apr. 16, 2013			Apr. 16, 2013			Sep. 23, 2013		Sep. 23, 2013		Feb. 18, 2014	Feb. 18, 2014	May 28, 2014	May 28, 2014
Exercise Price	$ 2.24	$ 2.90	$ 2.75		$ 504		$ 3.40		$ 3.40	$ 3.40		$ 3.40	$ 2.24		$ 2.80		$ 2.75	$ 2.56	$ 2.90	$ 3.70
Number of Warrants Outstanding	7,445			5,178		12	1,460	1,460		757	1,107			2,452	147	147	1,872	293	2,700	216