Income Taxes - Deferred Tax Assets (Details) - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014
Income Tax Disclosure [Abstract]
Net operating tax loss and capital loss carryforwards	$ 65,783	$ 60,380
Capitalized research and development costs	2,890	0
Research and development tax credits	950	534
Deferred compensation	106	168
Other accruals and reserves	1,092	670
Basis of intangible assets	4,197	4,610
Total deferred tax asset	75,018	66,362
Less valuation allowance	(75,018)	(66,362)
Net deferred tax asset	$ 0	$ 0