Goodwill and Other Intangible Assets - Schedule of Change in Net Carrying Amount of Goodwill by Segment (Detail) $ in Thousands	9 Months Ended
	Oct. 03, 2020 USD ($)
Goodwill [Line Items]
Balance, beginning of period	$ 2,201,063
Other	(821)
Translation	(4,454)
Balance, end of period	2,195,788
Steel Mills [Member]
Goodwill [Line Items]
Balance, beginning of period	591,986
Balance, end of period	591,986
Steel Products [Member]
Goodwill [Line Items]
Balance, beginning of period	879,500
Other	(821)
Translation	(4,454)
Balance, end of period	874,225
Raw Materials [Member]
Goodwill [Line Items]
Balance, beginning of period	729,577
Balance, end of period	$ 729,577