Income Taxes (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Deferred tax assets
Net operating loss carryforwards	$ 32,704	$ 26,993
Research and development credits	853	701
Depreciation and amortization	578	825
Accrued LifeCell settlement		252
Accrued expenses and other	259	191
Inventory reserve	417	425
Gross deferred tax asset	34,811	29,387
Valuation allowance	(34,811)	(29,387)
Net deferred tax asset	$ 0	$ 0