Income Taxes (Tables)

12 Months Ended

Dec. 31, 2013

Income Tax Disclosure [Abstract]

Differences Between the Company's Effective Tax Rate and the Statutory Tax Rate

The differences between the Company’s effective tax rate and the statutory tax rate in 2013, 2012, and 2011 are as follows:

	2013			2012			2011
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	$	—		$	—		$	—

Reconciliation of the Beginning and Ending Amount of Unrecognized Tax Benefits

A reconciliation of the beginning and ending amount of unrecognized tax benefits is as follows:

	2013		2012
Balance at January 1	$	—	$	—
Additions to current year tax positions		43		—
Additions to tax positions of prior years		241		—
Reductions for tax provisions of prior years		—		—
Balance at December 31	$	284	$	—

Components of Deferred Tax Assets and Liabilities

Significant components of the Company’s deferred tax assets and liabilities are as follows:

	2013			2012
Deferred tax assets:
Net federal and state operating losses	$	119,940		$	108,498
Research and development credits		37,348			36,142
Fixed assets		1,119			1,185
Reserve for inventories		1,612			1,654
Deferred revenue		2,151			2,645
Stock-based compensation		5,282			6,475
Foreign currency derivative		(207	)		1,851
Other		311			539
Total deferred tax assets		167,556			158,989
Valuation allowance		(167,556	)		(158,989	)
Total deferred tax liabilities		—			—
Net deferred tax assets	$	—		$	—