Goodwill and Other Intangible Assets - Schedule of Change in Net Carrying Amount of Goodwill by Segment (Detail) $ in Thousands	9 Months Ended
	Oct. 01, 2016 USD ($)
Goodwill [Line Items]
Balance, beginning of period	$ 2,011,278
Translation	15,563
Balance, end of period	2,026,841
Steel Mills [Member]
Goodwill [Line Items]
Balance, beginning of period	590,634
Balance, end of period	590,634
Steel Products [Member]
Goodwill [Line Items]
Balance, beginning of period	691,067
Translation	15,563
Balance, end of period	706,630
Raw Materials [Member]
Goodwill [Line Items]
Balance, beginning of period	729,577
Balance, end of period	$ 729,577