Income Taxes - Deferred Tax Assets and Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Assets
Deferred compensation	$ 4,025	$ 4,348
Loss and credit carryforwards	1,735	1,362
Accruals deductible for tax purposes when paid	189	247
State taxes	558	556
Depreciation	30	15
Unrealized gain	184
Other	31	39
Gross deferred tax assets	6,752	6,567
Deferred tax asset valuation allowance	(5,590)	(2,505)	$ (2,650)	$ (2,349)
Gross deferred tax assets less valuation allowance	1,162	4,062
Liabilities
Amortization	(1,433)
Depreciation	(393)	(197)
Deferred compensation	(201)	(32)
Gross deferred tax liabilities	(2,027)	(229)
Net deferred tax liabilities	(865)
Net deferred tax assets		3,833
Net non-current assets	767	3,861	$ 6,886
Net non-current liabilities	$ (1,632)	$ (28)