Income Taxes - Differences Between the Company's Effective Tax Rate and the Statutory 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]
Income tax benefit at federal statutory rate (35%)	$ (10,538)	$ (13,678)	$ (19,932)
State and local income taxes net of federal tax benefit	(839)	(1,470)	(2,503)
Permanent items	738	754	890
Rate change	1,892	1,147	(2,500)
Expiration of attribute carryforwards	242	5,135	2,884
Research and development tax credits	(1,206)	829	(2,108)
Other	1,144	281	731
Change in valuation allowance	8,567	7,002	22,538
Income tax expense