Debt and Warrants - Summary of Convertible Notes Including Principal and Accrued Interest (Detail) - USD ($) $ in Thousands	May. 04, 2015	Dec. 31, 2014
Debt Instrument [Line Items]
Convertible notes, principal amount	$ 43,000
Convertible notes, accrued interest	5,221	$ 4,153
July 2012 Convertible Notes [Member]
Debt Instrument [Line Items]
Convertible notes, principal amount	10,000
Convertible notes, accrued interest	2,368
January 2013 Convertible Notes [Member]
Debt Instrument [Line Items]
Convertible notes, principal amount	7,000
Convertible notes, accrued interest	1,342
October 2013 Convertible Notes [Member]
Debt Instrument [Line Items]
Convertible notes, principal amount	5,000
Convertible notes, accrued interest	617
March 2014 Convertible Notes [Member]
Debt Instrument [Line Items]
Convertible notes, principal amount	8,000
Convertible notes, accrued interest	726
March 2015 Convertible Notes [Member]
Debt Instrument [Line Items]
Convertible notes, principal amount	13,000
Convertible notes, accrued interest	$ 168