Segment Information - Results Footnote (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018	Dec. 31, 2018
Operating income (loss)
Corporate SG & A	$ (106,250)	$ (101,031)	$ (217,288)	$ (207,462)
Profit sharing	(22,871)	(42,335)	(46,548)	(68,997)
Operating income (loss)	285,032	501,887	576,874	825,284
Gross profit	421,166	652,082	854,736	1,115,498
Assets
Accounts receivable	1,072,879		1,072,879		$ 1,043,756
Cash and equivalents	972,561		972,561		828,220
Short-term Investments	114,154		114,154		228,783
Inventories	1,802,759		1,802,759		1,859,168
Property, plant and equipment, net	2,947,243		2,947,243		2,945,767
Other assets	104,306		104,306		25,166
Total assets	7,857,914		7,857,914		$ 7,703,563
Operating Segment | Other
Operating income (loss)
Corporate SG & A	(18,000)	(14,500)	(40,600)	(30,200)
Company-wide equity-based compensation	(8,400)	(8,500)	(17,400)	(17,000)
Profit sharing	(21,300)	(40,600)	(44,300)	(66,200)
Other, net	(1,500)		(3,800)	(5,600)
Operating income (loss)	(49,153)	(63,618)	(106,073)	(119,024)
Assets
Cash and equivalents	916,500		916,500
Short-term Investments	109,200		109,200
Accounts receivable	6,000		6,000
Inventories	35,100		35,100
Property, plant and equipment, net	176,500		176,500
Intra-company debt	8,300		8,300
Other assets	56,300		56,300
Total assets	1,307,873		1,307,873
Operating Segment | Metals Recycling Operations
Operating income (loss)
Operating income (loss)	7,619	22,638	24,581	47,353
Assets
Total assets	987,702		987,702
Eliminations
Operating income (loss)
Operating income (loss)	4,491	(4,771)	6,590	(5,036)
Gross profit	4,500	$ (4,800)	6,600	$ (5,000)
Assets
Accounts receivable	(57,200)		(57,200)
Intra-company debt	(8,300)		(8,300)
Other assets	(7,800)		(7,800)
Total assets	$ (73,334)		$ (73,334)