Segments - Segments (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 28, 2013	Sep. 29, 2012	Sep. 28, 2013	Sep. 29, 2012	Dec. 31, 2012
Segment Reporting Information [Line Items]
Net sales to external customers	$ 4,940,936	$ 4,801,206	$ 14,157,296	$ 14,977,999
Intercompany sales
Earnings before income taxes and noncontrolling interests	248,202	191,775	553,862	633,030
Segment assets	15,091,776		15,091,776		14,152,059
Steel Mills [Member]
Segment Reporting Information [Line Items]
Net sales to external customers	3,435,884	3,319,518	9,901,471	10,682,810
Intercompany sales	652,077	670,876	1,924,222	1,997,879
Earnings before income taxes and noncontrolling interests	310,591	218,367	819,951	944,598
Segment assets	8,137,612		8,137,612		7,894,974
Steel Products [Member]
Segment Reporting Information [Line Items]
Net sales to external customers	964,153	1,006,366	2,690,604	2,840,055
Intercompany sales	24,909	17,179	75,036	52,958
Earnings before income taxes and noncontrolling interests	31,018	(10,252)	51,167	(34,094)
Segment assets	2,986,752		2,986,752		2,935,146
Raw Materials [Member]
Segment Reporting Information [Line Items]
Net sales to external customers	540,899	475,322	1,565,221	1,455,134
Intercompany sales	2,391,502	2,080,150	6,738,485	7,441,529
Earnings before income taxes and noncontrolling interests	(493)	14,535	13,261	44,223
Segment assets	3,746,813		3,746,813		3,400,690
Corporate/Eliminations [Member]
Segment Reporting Information [Line Items]
Intercompany sales	(3,068,488)	(2,768,205)	(8,737,743)	(9,492,366)
Earnings before income taxes and noncontrolling interests	(92,914)	(30,875)	(330,517)	(321,697)
Segment assets	$ 220,599		$ 220,599		$ (78,751)