Inventories (Details) - USD ($) $ in Thousands	Dec. 31, 2015		Dec. 31, 2014
Inventory Disclosure [Abstract]
Finished goods	$ 308,462		$ 262,769
Raw materials and work in process	144,886	[1]	53,152
Stores, supplies and other	55,380		42,440
Total inventories	$ 508,728		$ 358,361

[1] Balance at December 31, 2015 includes $39.1 million of work in process related to the Lithium product category.