Consolidated Statements of Operations (USD $) In Thousands, except Share data, unless otherwise specified	3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012
Income Statement [Abstract]
Net sales	$ 864,647	$ 1,034,867
Cost of sales	636,838	862,230
Gross profit	227,809	172,637
Selling, general and administrative expenses	33,754	27,012
Income from operations	194,055	145,625
Other income (expense)
Interest expense	(6,281)	(12,177)
Other income, net	3,519	1,347
Income before income taxes	191,293	134,795
Provision for income taxes	67,946	46,982
Net income	$ 123,347	$ 87,813
Earnings per share:
Basic	$ 1.84	$ 1.32
Diluted	$ 1.84	$ 1.31
Weighted average shares outstanding:
Basic	66,625,536	66,109,297
Diluted	66,908,869	66,558,517
Dividends per common share	$ 0.1875	$ 0.0738