Segments - Segments (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Jul. 05, 2014	Jun. 29, 2013	Jul. 05, 2014	Jun. 29, 2013	Dec. 31, 2013
Segment Reporting Information [Line Items]
Net sales	$ 5,291,075	$ 4,665,588	$ 10,399,519	$ 9,216,360
Earnings before income taxes and noncontrolling interests	241,865	152,332	449,366	305,660
Segment assets	15,310,888		15,310,888		15,203,283
Steel Mills [Member]
Segment Reporting Information [Line Items]
Earnings before income taxes and noncontrolling interests	368,138	237,102	685,935	509,360
Segment assets	8,572,357		8,572,357		8,365,023
Steel Products [Member]
Segment Reporting Information [Line Items]
Earnings before income taxes and noncontrolling interests	42,612	32,073	44,332	20,149
Segment assets	2,999,733		2,999,733		2,861,403
Raw Materials [Member]
Segment Reporting Information [Line Items]
Earnings before income taxes and noncontrolling interests	(9,635)	12,218	(1,276)	13,754
Segment assets	3,952,359		3,952,359		3,956,913
Net Sales To External Customers [Member]
Segment Reporting Information [Line Items]
Net sales	5,291,075	4,665,588	10,399,519	9,216,360
Net Sales To External Customers [Member] | Steel Mills [Member]
Segment Reporting Information [Line Items]
Net sales	3,674,140	3,197,433	7,281,904	6,465,587
Net Sales To External Customers [Member] | Steel Products [Member]
Segment Reporting Information [Line Items]
Net sales	1,035,923	937,104	1,910,092	1,726,451
Net Sales To External Customers [Member] | Raw Materials [Member]
Segment Reporting Information [Line Items]
Net sales	581,012	531,051	1,207,523	1,024,322
Intercompany Eliminations [Member]
Segment Reporting Information [Line Items]
Net sales	0	0	0	0
Intercompany Eliminations [Member] | Steel Mills [Member]
Segment Reporting Information [Line Items]
Net sales	742,200	639,425	1,451,066	1,272,145
Intercompany Eliminations [Member] | Steel Products [Member]
Segment Reporting Information [Line Items]
Net sales	26,542	30,855	48,042	50,127
Intercompany Eliminations [Member] | Raw Materials [Member]
Segment Reporting Information [Line Items]
Net sales	2,443,492	2,183,495	4,971,498	4,346,983
Intercompany Eliminations [Member] | Corporate/Eliminations [Member]
Segment Reporting Information [Line Items]
Net sales	(3,212,234)	(2,853,775)	(6,470,606)	(5,669,255)
Earnings before income taxes and noncontrolling interests	(159,250)	(129,061)	(279,625)	(237,603)
Segment assets	$ (213,561)		$ (213,561)		$ 19,944