Closing of Merger and Financing Transaction - Summary of Business Acquisition, ProForma Information (Detail) (USD $) In Thousands, except Per Share data, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Business Acquisition [Line Items]
Revenues	$ 401	$ 1,431
Net loss	(37,652)	(28,358)
Pro Forma Results [Member]
Business Acquisition [Line Items]
Revenues		1,456	2,150
Net loss		$ (30,420)	$ (22,149)
Earnings per share		$ (0.85)	$ (0.65)