Income Taxes (Tables)

12 Months Ended

Dec. 31, 2015

Amounts for the years ended December 31 were as follows (in thousands):

Deferred Tax Assets	2015			2014
Net operating losses	$	83,143		$	85,510
Credit carryovers		19,903			19,903
Depreciation and amortization		13,944			14,922
Accruals and reserves		609			808
Capital loss carryover		85			100
Other		3,114			3,660
Total deferred tax assets		120,798			124,903
Less valuation allowance		(120,798	)		(124,903	)
Net deferred tax assets	$	—		$	—

Reconciliation Between Provision for Income Taxes and Income Taxes

The reconciliation between the provision for income taxes and income taxes computed using the U.S. federal statutory corporate tax rate were as follows for the years ended December 31 (in thousands):

	2015			2014			2013
Computed “expected” tax benefit	$	(3,152	)	$	(5,607	)	$	(10,621	)
State income taxes, net of federal benefit		—			(444	)		(1,947	)
Tax effect of:
Change in valuation allowance		(4,069	)		5,102			13,074
Rate change		3,524			—			—
Expiration of prior year credits and net operating losses		786			675			(237	)
Research and development and other tax credits carryovers		—			—			(672	)
Stock compensation		376			274			337
Uncertain tax positions		3,074			—			—
Other		(539	)		—			66
Provision for income taxes	$	—		$	—		$	—

Summary of Activity Related to Unrecognized Tax Benefits

The following table summarizes the activity related to our unrecognized tax benefits (in thousands):

	2015		2014		2013
Beginning balance	$	582	$	—	$	—
Increases related to prior year tax positions		3,758		—		—
Increases related to current year tax positions		—		582		—
Ending balance	$	4,340	$	582	$	—