Other Noncurrent Liabilities (Details) - USD ($) $ in Thousands	Sep. 30, 2018	Jan. 01, 2018	Dec. 31, 2017
Other Liabilities Disclosure [Abstract]
Pension and retiree medical obligations	$ 85,743		$ 99,646
Transition tax payable	25,510		27,877
Liability for uncertain tax positions	1,047		1,047
Deferred revenue	3,271	$ 3,297	3,297
Liability for construction of new leased facility	11,616		0
Contingent consideration for acquisition	3,375		0
Other	24,063		23,818
Total other noncurrent liabilities	$ 154,625		$ 155,685