Income Taxes (Details 3) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2012	Dec. 31, 2011
Deferred tax assets:
Net operating loss carryforwards	$ 24,211	$ 20,146
State income taxes	(7)	4
Deferred revenue	4,978	6,615
Research and development and other credits	9,263	8,167
Reserves and accruals recognized in different periods	4,636	4,616
Basis difference in investment	1,032	1,108
Capitalized R&D expenses	1,566	1,407
Other	159	0
Total deferred tax assets	45,838	42,063
Deferred tax liabilities:
Depreciation and amortization	(4,282)	(4,086)
Valuation Allowance	(41,556)	(37,977)
Net deferred tax assets	$ 0	$ 0