Accrued Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Accrued Liabilities [Abstract]
Payroll and other compensation	$ 37,560	$ 27,186
Deferred revenue and customer advances	34,812	16,453
CRP Accrual	0	4,100
Pension and other postretirement benefits	8,261	8,444
Accrued income taxes	26,477	25,682
Other	49,857	49,455
Accrued liabilities	$ 156,967	$ 131,320