Federal Income Tax Provision Compared With Statutory Rates (Detail)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Income Tax Disclosure [Abstract]
Statutory regular federal income tax rate	(34.00%)	(34.00%)	(34.00%)
Change in valuation allowance	37.40%	27.00%	(13.00%)
Tax return to prior year provision adjustments		(0.90%)	16.20%
Expiration of federal net operating losses			28.20%
Reduction of net operating loss attributes		(3.10%)	(3.70%)
State tax benefit (net of federal benefit)	(3.30%)	(4.20%)	4.10%
Research credits	(1.90%)	(2.10%)
Foreign amounts with no tax benefit	(0.10%)	(0.20%)	(0.60%)
Non-deductible expenses	1.00%	1.60%	6.10%
Effect of change in rate	2.30%	14.20%
Other	(0.80%)	0.30%	0.50%
Total	0.60%	(1.40%)	3.80%