Segment Information - Results Footnote (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018	Dec. 31, 2018
Operating income (loss)
Corporate SG & A	$ (111,038)	$ (106,431)
Profit sharing	(23,677)	(26,662)
Operating income (loss)	291,842	323,397
Assets
Accounts receivable	1,143,395		$ 1,043,756
Cash and equivalents	791,444		828,220
Short-term Investments	173,723		228,783
Inventories	1,867,700		1,859,168
Property, plant and equipment, net	2,936,893		2,945,767
Other Assets, Noncurrent	97,419		25,166
Total assets	7,857,233		$ 7,703,563
Operating Segment | Other
Operating income (loss)
Corporate SG & A	(22,600)	(15,700)
Company-wide equity-based compensation	(9,000)	(8,500)
Profit sharing	(23,000)	(25,600)
Other, net	(2,300)	(5,600)
Operating income (loss)	(56,920)	(55,406)
Assets
Cash and equivalents	756,900
Short-term Investments	153,700
Accounts receivable	12,200
Inventories	36,100
Property, plant and equipment, net	152,600
Intra Company Debt	10,800
Other Assets, Noncurrent	48,500
Total assets	1,170,832
Operating Segment | Metals Recycling Operations
Operating income (loss)
Operating income (loss)	16,962	24,715
Assets
Total assets	982,844
Eliminations
Operating income (loss)
Operating income (loss)	2,099	$ (265)
Assets
Accounts receivable	(59,500)
Intra Company Debt	10,800
Other Assets, Noncurrent	(12,300)
Total assets	$ (82,555)