Segment Information - Results (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Segment Reporting Information
Net sales	$ 18,408,850	$ 9,601,482	$ 10,464,991
Operating income (loss)	4,301,105	847,142	986,880
Income (loss) before income taxes	4,209,070	705,478	875,337
Depreciation and amortization	347,653	325,789	321,082
Capital expenditures	1,006,239	1,198,055	451,945
Assets	12,531,234	9,265,562
U.S.
Segment Reporting Information
Net sales	17,290,933	9,089,194	9,927,874
Non-U.S.
Segment Reporting Information
Net sales	1,117,917	512,288	537,117
Operating Segment | Steel Operations
Segment Reporting Information
Net sales	14,023,133	7,455,637	8,234,179
Operating income (loss)	4,360,488	889,480	1,030,554
Income (loss) before income taxes	4,327,300	833,035	963,514
Depreciation and amortization	263,125	251,590	251,568
Capital expenditures	937,011	1,132,298	385,058
Assets	8,686,216	6,288,362
Operating Segment | Steel Operations | Other segments
Segment Reporting Information
Net sales	823,991	318,533	329,627
Operating Segment | Steel Operations | U.S.
Segment Reporting Information
Net sales	12,618,917	6,873,209	7,606,471
Operating Segment | Steel Operations | Non-U.S.
Segment Reporting Information
Net sales	580,225	263,895	298,081
Operating Segment | Metals Recycling Operations
Segment Reporting Information
Net sales	4,590,121	2,403,140	2,494,014
Operating income (loss)	181,986	32,991	16,308
Income (loss) before income taxes	181,579	27,753	11,432
Depreciation and amortization	55,620	50,099	46,538
Capital expenditures	46,360	32,875	46,959
Assets	1,266,920	1,116,051
Operating Segment | Metals Recycling Operations | Other segments
Segment Reporting Information
Net sales	2,406,649	1,335,216	1,296,007
Operating Segment | Metals Recycling Operations | U.S.
Segment Reporting Information
Net sales	1,658,843	820,262	972,200
Operating Segment | Metals Recycling Operations | Non-U.S.
Segment Reporting Information
Net sales	524,629	247,662	225,807
Operating Segment | Steel Fabrication Operations
Segment Reporting Information
Net sales	1,764,710	906,364	963,259
Operating income (loss)	365,250	120,575	119,099
Income (loss) before income taxes	362,473	116,625	114,359
Depreciation and amortization	9,961	10,819	11,768
Capital expenditures	12,939	15,234	12,446
Assets	1,195,396	376,658
Operating Segment | Steel Fabrication Operations | Other segments
Segment Reporting Information
Net sales	3,063	10,663	1,105
Operating Segment | Steel Fabrication Operations | U.S.
Segment Reporting Information
Net sales	1,761,078	895,227	960,657
Operating Segment | Steel Fabrication Operations | Non-U.S.
Segment Reporting Information
Net sales	569	474	1,497
Operating Segment | Other
Segment Reporting Information
Net sales	1,266,971	501,187	400,747
Operating income (loss)	(551,725)	(188,525)	(186,159)
Income (loss) before income taxes	(606,021)	(263,470)	(220,188)
Depreciation and amortization	18,947	13,281	11,208
Capital expenditures	9,929	17,648	7,482
Assets	1,523,830	1,571,188
Operating Segment | Other | Other segments
Segment Reporting Information
Net sales	2,382	434	469
Operating Segment | Other | U.S.
Segment Reporting Information
Net sales	1,252,095	500,496	388,546
Operating Segment | Other | Non-U.S.
Segment Reporting Information
Net sales	12,494	257	11,732
Eliminations
Segment Reporting Information
Net sales	(3,236,085)	(1,664,846)	(1,627,208)
Operating income (loss)	(54,894)	(7,379)	7,078
Income (loss) before income taxes	(56,261)	(8,465)	6,220
Assets	(141,128)	(86,697)
Eliminations | Other segments
Segment Reporting Information
Net sales	$ (3,236,085)	$ (1,664,846)	$ (1,627,208)