Income Taxes (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Deferred tax assets:
Net operating losses	$ 37,715	$ 53,099
Research & other credits	1,527	2,227
Other	2,172	1,447
Total deferred tax assets	41,414	56,773
Valuation allowance	(41,414)	(56,773)
Federal
Deferred tax assets:
Income Tax Expense (Benefit)	$ 0	$ 0	$ 0