Segment Information - Results (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2022	Jun. 30, 2021	Jun. 30, 2022	Jun. 30, 2021	Dec. 31, 2021
Segment Reporting Information
Net sales	$ 6,212,878	$ 4,465,308	$ 11,782,780	$ 8,009,905
Operating income (loss)	1,618,063	955,735	3,112,930	1,549,934
Income (loss) before income taxes	1,596,417	930,798	3,054,147	1,497,657
Depreciation and amortization	95,701	87,047	183,247	173,966
Capital expenditures	164,142	277,206	323,472	587,069
Assets	13,711,214		13,711,214		$ 12,531,234
U.S.
Segment Reporting Information
Net sales	5,822,023	4,186,665	11,070,231	7,512,672
Non-U.S.
Segment Reporting Information
Net sales	390,855	278,643	712,549	497,233
Operating Segment | Steel Operations
Segment Reporting Information
Net sales	4,246,616	3,394,442	8,178,269	6,037,289
Operating income (loss)	1,102,725	1,012,997	2,265,735	1,650,408
Income (loss) before income taxes	1,086,795	1,003,355	2,239,011	1,629,414
Depreciation and amortization	73,962	66,140	140,644	132,318
Capital expenditures	135,864	257,250	272,054	539,848
Assets	9,305,567		9,305,567
Operating Segment | Steel Operations | Other segments
Segment Reporting Information
Net sales	104,594	159,923	273,751	292,086
Operating Segment | Steel Operations | U.S.
Segment Reporting Information
Net sales	3,929,646	3,086,393	7,502,848	5,487,309
Operating Segment | Steel Operations | Non-U.S.
Segment Reporting Information
Net sales	212,376	148,126	401,670	257,894
Operating Segment | Metals Recycling Operations
Segment Reporting Information
Net sales	1,355,982	1,151,106	2,499,199	2,231,018
Operating income (loss)	54,443	47,596	99,403	98,159
Income (loss) before income taxes	53,446	48,396	99,176	97,735
Depreciation and amortization	13,021	14,070	26,275	27,940
Capital expenditures	15,199	7,324	26,756	31,242
Assets	1,371,995		1,371,995
Operating Segment | Metals Recycling Operations | Other segments
Segment Reporting Information
Net sales	706,247	575,407	1,269,839	1,185,312
Operating Segment | Metals Recycling Operations | U.S.
Segment Reporting Information
Net sales	476,093	449,872	924,136	813,750
Operating Segment | Metals Recycling Operations | Non-U.S.
Segment Reporting Information
Net sales	173,642	125,827	305,224	231,956
Operating Segment | Steel Fabrication Operations
Segment Reporting Information
Net sales	1,090,198	331,715	2,020,298	590,735
Operating income (loss)	599,191	28,409	1,066,066	38,263
Income (loss) before income taxes	596,763	27,871	1,061,962	36,935
Depreciation and amortization	2,433	2,406	4,863	5,081
Capital expenditures	4,569	3,077	8,259	5,698
Assets	1,475,131		1,475,131
Operating Segment | Steel Fabrication Operations | Other segments
Segment Reporting Information
Net sales	4,444	862	4,563	2,898
Operating Segment | Steel Fabrication Operations | U.S.
Segment Reporting Information
Net sales	1,085,710	330,709	2,015,552	587,671
Operating Segment | Steel Fabrication Operations | Non-U.S.
Segment Reporting Information
Net sales	44	144	183	166
Operating Segment | Other
Segment Reporting Information
Net sales	335,739	325,350	634,197	632,831
Operating income (loss)	(162,194)	(127,694)	(336,729)	(218,607)
Income (loss) before income taxes	(164,143)	(142,894)	(363,772)	(247,493)
Depreciation and amortization	6,285	4,431	11,465	8,627
Capital expenditures	8,510	9,555	16,403	10,281
Assets	1,710,915		1,710,915
Operating Segment | Other | Other segments
Segment Reporting Information
Net sales	372	1,113	1,030	1,672
Operating Segment | Other | U.S.
Segment Reporting Information
Net sales	330,574	319,691	627,695	623,942
Operating Segment | Other | Non-U.S.
Segment Reporting Information
Net sales	4,793	4,546	5,472	7,217
Eliminations
Segment Reporting Information
Net sales	(815,657)	(737,305)	(1,549,183)	(1,481,968)
Operating income (loss)	23,898	(5,573)	18,455	(18,289)
Income (loss) before income taxes	23,556	(5,930)	17,770	(18,934)
Assets	(152,394)		(152,394)
Eliminations | Other segments
Segment Reporting Information
Net sales	$ (815,657)	$ (737,305)	$ (1,549,183)	$ (1,481,968)