Income Taxes (Tables)

12 Months Ended

Dec. 31, 2013

Income Tax Disclosure [Abstract]

Summary of Deferred Tax Assets

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

Deferred Tax Assets	2013			2012
Net operating losses	$	82,753		$	76,152
Credit carryovers		19,903			18,405
Depreciation and amortization		12,915			8,210
Accruals and reserves		322			414
Capital loss carryover		100			45
Other		3,808			3,501
Total deferred tax assets		119,801			106,727
Less valuation allowance		(119,801	)		(106,727	)
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):

	2013			2012			2011
Computed “expected” tax benefit	$	(10,621	)	$	(7,712	)	$	(2,606	)
State income taxes, net of federal benefit		(1,947	)		451			(545	)
Tax effect of:
Change in valuation allowance		13,074			(37,179	)		2,185
Expiration of prior year credits and net operating losses		(237	)		45,382			1,880
Research and development and other tax credits carryovers		(672	)		(1,097	)		(1,468	)
Stock compensation		337			358			297
Other		66			(203	)		257
Provision for income taxes	$	—		$	—		$	—