Segment Information - Other Footnote (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017	Dec. 31, 2017
Operating income (loss)
Corporate SG & A	$ (106,431)	$ (102,933)
Profit sharing	(26,662)	(27,231)
Operating income (loss)	323,397	334,566
Assets
Cash and equivalents	985,824		$ 1,028,649
Short-term Investments	40,000
Inventories	1,600,058		1,519,347
Property, plant and equipment, net	2,657,937		2,675,904
Other	26,606		27,684
Total assets	6,972,813		$ 6,855,732
Other
Operating income (loss)
Corporate SG & A	(15,700)	(12,400)
Company-wide equity-based compensation	(8,500)	(9,600)
Profit sharing	(25,600)	(26,500)
Other, net	(5,600)	(5,500)
Operating income (loss)	(55,406)	(53,970)
Assets
Cash and equivalents	970,500
Short-term Investments	40,000
Inventories	28,400
Property, plant and equipment, net	161,700
Intra Company Debt	12,900
Other	37,400
Total assets	1,250,869
Metals Recycling Operations
Operating income (loss)
Operating income (loss)	24,715	$ 17,849
Assets
Total assets	$ 1,006,510