Income Taxes - Unrecognized Tax Benefits (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Unrecognized Tax Benefits [Roll Forward]
Beginning of year balance	$ 193	$ 185	$ 43
Additions based on prior year tax positions	3	2	130
Additions based on current year tax positions	78	11	12
Reduction for prior year tax positions	(19)	(5)	0
End of year balance	$ 255	$ 193	$ 185