Income Taxes - Components of Deferred Tax Assets and Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Deferred tax assets (liabilities):
Start-up costs	$ 1,208	$ 1,239
Capitalized research and development costs	612	728
Reserves and accruals	8,180	7,465
Property and equipment	55
Research and development credit	1,194	1,334
Lease liability	118
State and local taxes	4
Net operating loss carryforwards	27,860	22,721
Total gross deferred tax assets	39,231	33,487
Valuation allowance	(36,349)	(29,904)
Deferred tax assets, net of valuation allowance	2,882	3,583
Intangible assets	(3,396)	(5,385)
Operating lease right-of-use assets	(188)
Property and equipment		(42)
Total gross deferred tax liabilities	(3,584)	(5,427)
Net deferred tax liability	(702)	(1,844)
Net deferred tax liability
Deferred tax liability associated with indefinite-lived intangible asset	3,500	5,100
U.S. federal
Net deferred tax liability
Deferred tax asset associated with net operating loss carryforwards that do not expire	2,400	$ 3,300
State
Net deferred tax liability
Deferred tax asset associated with net operating loss carryforwards that do not expire	$ 400