Other Noncurrent Liabilities (Details) - USD ($) $ in Thousands	Jun. 30, 2021	Dec. 31, 2020
Other Liabilities Disclosure [Abstract]
Pension and retiree medical obligations	$ 94,956	$ 99,417
Transition tax payable	14,128	14,208
Liability for uncertain tax positions	949	1,071
Deferred revenue	35,239	30,354
Lease liability	91,950	94,250
Other	21,560	27,497
Total other noncurrent liabilities	$ 258,782	$ 266,797