Income Taxes (Tables)

12 Months Ended

Dec. 31, 2015

Income Tax Disclosure [Abstract]

Reconciliation of Federal Statutory Income Tax Rate

Reconciliation of the Federal statutory income tax rate of 34% to the effective rate is as follows:

	2015			2014			2013
Federal statutory income tax rate		34.00	%		34.00	%		34.00	%
State taxes, net of federal benefit		3.45			3.45			3.45
Permanent differences-derivative loss (gain)		—			(9.10	)		0.11
Permanent differences-other		(4.66	)		2.24			(1.07	)
Research and development (“R&D”) credit		0.95			2.73			4.91
Other		0.64			0.61			0.64
Increase in valuation allowance		(34.38	)		(33.93	)		(42.04	)
		0.00	%		0.00	%		0.00	%

Significant Components of Deferred Tax Assets and Liabilities

The tax effects of temporary differences and net operating losses that give rise to significant components of deferred tax assets and liabilities consist of the following:

	December 31,
Deferred tax assets (liabilities)	2015			2014
Deferred revenue	$	7,490		$	315
Basis difference in equipment		(1,013	)		(975	)
Basis difference in intangibles		1,122			1,102
Accrued liabilities and other		1,563			360
R&D credit		11,138			11,316
Stock options		1,151			462
Net operating loss carry-forward		63,509			59,481
		84,960			72,061
Less: valuation allowance		(84,960	)		(72,061	)
	$	—		$	—