Other Noncurrent Liabilities (Details) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
Other Liabilities Disclosure [Abstract]
Pension and retiree medical obligations	$ 100,491	$ 99,646
Transition tax payable	27,877	27,877
Liability for uncertain tax positions	1,047	1,047
Deferred revenue	3,489	3,297
Liability for construction of new leased facility	5,801	0
Other	22,210	23,818
Total other noncurrent liabilities	$ 160,915	$ 155,685