Accrued Liabilities - Components of Accrued Liabilities (Details) - USD ($) $ in Thousands	Sep. 30, 2017	Dec. 31, 2016	Dec. 31, 2015
Accrued Liabilities
Accrued product related costs	$ 4,681	$ 5,556
Accrued income taxes	10,157	9,826
Accrued property and other taxes	2,435	1,917
Accrued professional fees	1,687	1,633
Dividends payable	1,317	1,309
Remediation reserves	17,633	18,176	$ 20,603
Other accrued liabilities	6,081	7,291
Total accrued liabilities	$ 43,991	$ 45,708