Goodwill and Other Intangible Assets - Schedule of Change in Net Carrying Amount of Goodwill by Segment (Detail) $ in Thousands	6 Months Ended
	Jul. 04, 2015 USD ($)
Goodwill [Line Items]
Balance, beginning of period	$ 2,068,664
Translation	(18,566)
Other	(4,000)
Balance, end of period	2,046,098
Steel Mills [Member]
Goodwill [Line Items]
Balance, beginning of period	594,402
Other	(4,000)
Balance, end of period	590,402
Steel Products [Member]
Goodwill [Line Items]
Balance, beginning of period	744,685
Translation	(18,566)
Balance, end of period	726,119
Raw Materials [Member]
Goodwill [Line Items]
Balance, beginning of period	729,577
Balance, end of period	$ 729,577