Segment Information - Results (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023	Dec. 31, 2023
Segment Reporting Information
Total net sales	$ 4,694,003	$ 4,893,206
Operating income (loss)	750,975	835,360
Income (loss) before income taxes	765,781	847,789
Depreciation and amortization	115,252	107,694
Capital expenditures	374,310	226,319
Assets	15,026,750		$ 14,908,420
U.S.
Segment Reporting Information
Total net sales	4,278,488	4,451,020
Non-U.S.
Segment Reporting Information
Total net sales	415,515	442,186
Operating Segment | Steel Operations
Segment Reporting Information
Total net sales	3,514,528	3,171,699
Operating income (loss)	670,931	341,908
Income (loss) before income taxes	674,812	343,089
Depreciation and amortization	87,507	84,532
Capital expenditures	95,833	120,628
Assets	8,890,778
Operating Segment | Steel Operations | Other segments
Segment Reporting Information
Total net sales	148,291	83,209
Operating Segment | Steel Operations | U.S.
Segment Reporting Information
Total net sales	3,133,610	2,847,248
Operating Segment | Steel Operations | Non-U.S.
Segment Reporting Information
Total net sales	232,627	241,242
Operating Segment | Metals Recycling Operations
Segment Reporting Information
Total net sales	1,094,041	1,161,927
Operating income (loss)	18,728	39,688
Income (loss) before income taxes	21,509	45,549
Depreciation and amortization	18,470	14,365
Capital expenditures	31,864	19,697
Assets	1,507,536
Operating Segment | Metals Recycling Operations | Other segments
Segment Reporting Information
Total net sales	524,568	578,459
Operating Segment | Metals Recycling Operations | U.S.
Segment Reporting Information
Total net sales	390,923	382,803
Operating Segment | Metals Recycling Operations | Non-U.S.
Segment Reporting Information
Total net sales	178,550	200,665
Operating Segment | Steel Fabrication Operations
Segment Reporting Information
Total net sales	451,763	868,804
Operating income (loss)	178,340	551,272
Income (loss) before income taxes	178,367	551,412
Depreciation and amortization	2,682	2,331
Capital expenditures	5,436	4,496
Assets	768,832
Operating Segment | Steel Fabrication Operations | Other segments
Segment Reporting Information
Total net sales	4,584	36
Operating Segment | Steel Fabrication Operations | U.S.
Segment Reporting Information
Total net sales	446,096	868,702
Operating Segment | Steel Fabrication Operations | Non-U.S.
Segment Reporting Information
Total net sales	1,083	66
Operating Segment | Aluminum Operations
Segment Reporting Information
Operating income (loss)	(13,531)	(2,422)
Income (loss) before income taxes	(13,811)	(2,406)
Depreciation and amortization	20
Capital expenditures	237,328	74,820
Assets	1,606,906
Operating Segment | Other
Segment Reporting Information
Total net sales	311,114	352,480
Operating income (loss)	(97,872)	(96,666)
Income (loss) before income taxes	(89,073)	(91,079)
Depreciation and amortization	6,573	6,466
Capital expenditures	3,849	6,678
Assets	3,121,797
Operating Segment | Other | U.S.
Segment Reporting Information
Total net sales	307,859	352,267
Operating Segment | Other | Non-U.S.
Segment Reporting Information
Total net sales	3,255	213
Eliminations
Segment Reporting Information
Total net sales	(677,443)	(661,704)
Operating income (loss)	(5,621)	1,580
Income (loss) before income taxes	(6,023)	1,224
Assets	(869,099)
Eliminations | Other segments
Segment Reporting Information
Total net sales	$ (677,443)	$ (661,704)