Income Taxes (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Components of profit (loss) before provision for income taxes
Domestic	$ (28,200)	$ 3,502	$ (38,872)
Foreign	(2,295)	72	30
Profit (loss) before taxes	(30,495)	3,574	(38,842)
Deferred Tax Assets:
Net operating loss carryforward	81,699	72,016
Capitalization of research and development expense	1,945	2,763
Credit carryforwards	8,118	7,024
Depreciation	2,403	2,603
Non-Qualified Stock Options	4,437	4,213
Other temporary differences	1,813	1,958
Total deferred tax assets	100,415	90,577
Valuation allowance	(100,405)	(90,558)
Net deferred tax asset	10	19
Deferred Tax Liabilities:
Other temporary differences	(10)	(19)
Difference between income tax benefit computed at the federal statutory rate and the provision for income taxes
Federal income tax at statutory federal rate (as a percent)	34.00%	34.00%	34.00%
State taxes (as a percent)	3.50%	7.80%	5.00%
Permanent differences (as a percent)	(1.90%)	19.60%	(2.40%)
Tax credits (as a percent)	2.70%	(10.50%)	2.40%
State rate change on deferred balances (as a percent)	(0.40%)	3.10%	1.40%
Expiration of net operating losses and credits (as a percent)	(5.80%)	49.20%	(1.60%)
Other (as a percent)	0.20%	9.80%	1.00%
Change in valuation allowance (as a percent)	(32.30%)	(113.00%)	(39.80%)
Total (as a percent)	0.00%	0.00%	0.00%
Unrecognized tax benefits	0	0	0
Accrued interest or penalties related to uncertain tax positions	$ 0	$ 0	$ 0