Consolidated Statements of Operations (USD $) In Thousands, except Share data, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Income Statement [Abstract]
Net sales	$ 1,004,165	$ 821,175	$ 2,807,859	$ 2,770,000
Cost of sales	699,694	648,996	2,002,092	2,223,288
Gross profit	304,471	172,179	805,767	546,712
Selling, general and administrative expenses	37,869	29,662	109,883	87,592
Income from operations	266,602	142,517	695,884	459,120
Other income (expense)
Interest expense	(3,297)	(11,934)	(14,921)	(35,682)
Debt retirement costs	0	(7,082)	0	(7,082)
Gain from sales of equity securities	0	477	0	16,429
Other (expense) income, net	(287)	1,222	3,137	3,676
Income before income taxes	263,018	125,200	684,100	436,461
Provision for income taxes	92,728	38,236	244,647	146,183
Net income	$ 170,290	$ 86,964	$ 439,453	$ 290,278
Earnings per share:
Basic	$ 2.55	$ 1.30	$ 6.57	$ 4.36
Diluted	$ 2.54	$ 1.30	$ 6.54	$ 4.33
Weighted average shares outstanding:
Basic	66,628,747	66,311,958	66,628,027	66,240,225
Diluted	66,905,554	66,656,760	66,903,379	66,621,520
Dividends per common share	$ 0.2250	$ 0.1875	$ 0.6000	$ 0.3350