Basis of Presentation (Details) - USD ($) $ in Thousands	Mar. 31, 2017	Dec. 31, 2016
Consolidated Balance Sheet Line Item
Other current assets	$ 11,431	$ 10,638
Deferred income taxes	42,779	45,839
Accrued liabilities	(42,463)	(45,708)
Post retirement obligations	(7,008)	(7,006)
Other long-term obligations	$ (7,607)	$ (5,580)