Accrued Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Accrued Liabilities [Abstract]
Payroll and benefits	$ 3,620	$ 3,659
Other	4,750	7,105
Accrued liabilities	$ 8,370	$ 10,764	[1]

[1] See Note 4.