Accrued Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014
Accrued Liabilities [Abstract]
Payroll and other compensation	$ 27,186	$ 41,948
Deferred revenue	16,453	25,344
CRP Accrual	4,100	19,900
Pension and other postretirement benefits	8,444	8,233
Accrued income taxes	25,682	21,755
Other	49,455	44,217
Accrued liabilities	$ 131,320	$ 161,397