Income Taxes - Income Tax Provision Amount Computed by Applying Statutory Income Tax Rate (Detail) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Income Tax Disclosure [Abstract]
Tax at statutory rate	$ (11,763)	$ (14,943)	$ (6,848)
Current year net operating losses and temporary differences for which no tax benefit is recognized	12,458	5,351	8,549
Deferred revenue	(2,704)	6,672
Non-cash expense (credit) related to financings	(16)	2,570	(1,995)
Other permanent differences	2,028	350	294
Provision for income taxes