Supplemental Quarterly Information (Detail) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended																12 Months Ended
	Dec. 31, 2011		Sep. 30, 2011		Jun. 30, 2011		Mar. 31, 2011		Dec. 31, 2010		Sep. 30, 2010		Jun. 30, 2010		Mar. 31, 2010		Dec. 31, 2011		Dec. 31, 2010		Dec. 31, 2009
Quarterly Financial Information [Line Items]
Sales and other operating revenues	$ 6,761,300		$ 7,240,400		$ 7,415,900		$ 6,271,700		$ 5,562,600		$ 5,209,000		$ 4,754,900		$ 4,699,300		$ 27,689,332		$ 20,225,764	[1]	$ 16,800,972	[1]
Income from continuing operations before income taxes	100,000		534,400		505,200		411,400		286,200		352,700		433,600		316,200		1,550,983		1,388,710	[1]	1,235,413	[1]
Income (loss) from continuing operations	(113,300)		335,700		280,000		238,500		149,500		197,400		263,200		169,500		740,932		779,559	[1]	713,854	[1]
Net income	$ (113,900)		$ 406,100		$ 311,600		$ 268,900		$ 174,100		$ 202,800		$ 272,300		$ 148,900		$ 872,702		$ 798,081	[1]	$ 837,621	[1]
Income (loss) from continuing operations per Common share
Basic	$ (0.59)		$ 1.74		$ 1.45		$ 1.23		$ 0.77		$ 1.03		$ 1.37		$ 0.89		$ 3.83		$ 4.06	[1]	$ 3.74	[1]
Diluted	$ (0.59)		$ 1.73		$ 1.44		$ 1.22		$ 0.77		$ 1.02		$ 1.36		$ 0.88		$ 3.81		$ 4.03	[1]	$ 3.71	[1]
Net income (loss) per Common share
Basic	$ (0.59)		$ 2.10		$ 1.61		$ 1.39		$ 0.90		$ 1.06		$ 1.42		$ 0.78		$ 4.51		$ 4.16	[1]	$ 4.39	[1]
Diluted	$ (0.59)		$ 2.09		$ 1.60		$ 1.38		$ 0.90		$ 1.05		$ 1.41		$ 0.77		$ 4.49		$ 4.13	[1]	$ 4.35	[1]
Cash dividend per Common share	$ 0.275		$ 0.275		$ 0.275		$ 0.275		$ 0.275		$ 0.275		$ 0.250		$ 0.250		$ 1.100		$ 1.050
Market price of Common Stock
High	$ 58.67	[2]	$ 69.71	[2]	$ 77.48	[2]	$ 76.11	[2]	$ 75.37	[2]	$ 61.92	[2]	$ 61.82	[2]	$ 59.71	[2]	$ 77.48	[2]	$ 75.37	[2]
Low	$ 42.10	[2]	$ 44.05	[2]	$ 62.53	[2]	$ 65.74	[2]	$ 61.01	[2]	$ 48.44	[2]	$ 49.55	[2]	$ 50.13	[2]	$ 42.10	[2]	$ 48.44	[2]

[1] Reclassified to conform to current presentation.

[2] Prices are as quoted on the New York Stock Exchange.