Other Noncurrent Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Other Liabilities, Noncurrent [Abstract]
Transition tax on foreign earnings	$ 273,048	$ 303,490
Wodgina Project acquisition consideration obligation	$ 0	$ 120,800
Operating Lease, Liability, Noncurrent, Statement of Financial Position [Extensible List]	us-gaap:OtherLiabilitiesNoncurrent	us-gaap:OtherLiabilitiesNoncurrent
Operating leases	$ 116,765	$ 114,686
Liabilities related to uncertain tax positions	14,683	21,169
Executive deferred compensation plan obligation	32,447	28,715
Environmental liabilities	36,298	33,058	$ 40,376
Asset retirement obligations	74,856	55,848
Tax indemnification liability	30,488	30,993
Other	50,792	45,777
Total	$ 629,377	$ 754,536