Income Taxes - Current and Long-Term Deferred Tax Assests and Liabilities (Details 4) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Operating Loss Carryforwards [Line Items]
Non-current deferred tax assets	$ 22,201	$ 20,694
Non-current deferred tax liabilities	(3,990)	(3,802)
Total net deferred tax assets	18,211	16,892
Total net deferred tax assets	$ 18,211	$ 16,892
Minimum | Operating Loss Carryforward [Member]
Operating Loss Carryforwards [Line Items]
Operating Loss Carryforwards, Expiration Date	Dec. 31, 2021
Maximum | Operating Loss Carryforward [Member]
Operating Loss Carryforwards [Line Items]
Operating Loss Carryforwards, Expiration Date	Dec. 31, 2038