Segments (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2012	Jul. 02, 2011	Jun. 30, 2012	Jul. 02, 2011	Dec. 31, 2011
Segment Reporting Information [Line Items]
Net sales to external customers	$ 5,104,199	$ 5,107,809	$ 10,176,793	$ 9,941,743
Earnings (loss) before income taxes and noncontrolling interests	216,193	477,287	441,255	743,542
Segment assets	14,766,566		14,766,566		14,570,350
Steel Mills [Member]
Segment Reporting Information [Line Items]
Net sales to external customers	3,476,661	3,569,786	7,102,800	7,017,983
Intercompany sales	698,565	632,055	1,316,209	1,216,668
Earnings (loss) before income taxes and noncontrolling interests	336,096	645,719	726,388	1,048,600
Segment assets	8,021,836		8,021,836		6,440,868
Steel Products [Member]
Segment Reporting Information [Line Items]
Net sales to external customers	991,444	875,365	1,833,689	1,607,504
Intercompany sales	18,993	14,233	35,779	24,247
Earnings (loss) before income taxes and noncontrolling interests	9,202	(10,010)	(23,842)	(45,905)
Segment assets	2,979,680		2,979,680		2,903,281
Raw Materials [Member]
Segment Reporting Information [Line Items]
Net sales to external customers	497,604	555,545	979,812	1,083,008
Intercompany sales	2,479,148	2,697,521	5,361,379	5,475,127
Earnings (loss) before income taxes and noncontrolling interests	15,116	53,835	29,688	114,089
Segment assets	3,050,833		3,050,833		2,925,651
All Other [Member]
Segment Reporting Information [Line Items]
Net sales to external customers	138,490	107,113	260,492	233,248
Intercompany sales	8,190	9,926	10,794	16,351
Earnings (loss) before income taxes and noncontrolling interests	412	1,074	(157)	4,277
Segment assets	188,256		188,256		152,107
Corporate/Eliminations [Member]
Segment Reporting Information [Line Items]
Intercompany sales	(3,204,896)	(3,353,735)	(6,724,161)	(6,732,393)
Earnings (loss) before income taxes and noncontrolling interests	(144,633)	(213,331)	(290,822)	(377,519)
Segment assets	$ 525,961		$ 525,961		$ 2,148,443