Inventories Breakdown of Inventories (Details) - USD ($) $ in Thousands	Jun. 30, 2015	Dec. 31, 2014
Inventory Disclosure [Abstract]
Finished goods	$ 380,899	$ 262,769
Raw materials	116,342	53,152
Work in process	50,131	0
Stores, supplies and other	54,653	42,440
Total inventories	$ 602,025	$ 358,361