Other Current Liabilities (Details) - USD ($) $ in Thousands	Jun. 30, 2018	Dec. 31, 2017
Other Liabilities Disclosure [Abstract]
Customer deposits and accrued rebates	$ 2,841	$ 3,102
Dividends payable	5,210	4,478
Accrued litigation, claims and professional fees	861	417
Current portion of environmental reserves	1,039	1,322
Other accrued expenses	5,736	6,153
Other current liabilities, Total	$ 15,687	$ 15,472