Goodwill and Other Intangible Assets - Schedule of Change in Net Carrying Amount of Goodwill by Segment (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020
Goodwill [Line Items]
Balance, beginning of period	$ 2,229,672	$ 2,201,063
Acquisitions	599,127	19,663
Translation	(1,455)	8,946
Balance, end of period	2,827,344	2,229,672
Steel Mills [Member]
Goodwill [Line Items]
Balance, beginning of period	612,470	591,986
Acquisitions	705	20,484
Balance, end of period	613,175	612,470
Steel Products [Member]
Goodwill [Line Items]
Balance, beginning of period	887,625	879,500
Acquisitions	553,704	(821)
Translation	(1,455)	8,946
Balance, end of period	1,439,874	887,625
Raw Materials [Member]
Goodwill [Line Items]
Balance, beginning of period	729,577	729,577
Acquisitions	44,718
Balance, end of period	$ 774,295	$ 729,577