Accrued Expenses and Other Liabilities Accrued Expenses and Other Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Accounts Payable and Accrued Liabilities, Current [Abstract]
Accrued stock based compensation	$ 13,458	$ 8,712
Accrued compensation	10,740	9,044
Accrued severance	304	483
Accrued and withheld taxes, other than income taxes	1,674	1,136
Accrued Environmental Loss Contingencies, Current	1,376	968
Financing lease obligation	1,207	1,123
Accrued health benefits	614	657
Accrued profit sharing	899	894
Deferred Revenue	693	0
Other	9,214	10,023
Accrued Liabilities, Current	$ 40,179	$ 33,040