Supplemental Quarterly Information (Detail) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended																12 Months Ended
	Dec. 31, 2012		Sep. 30, 2012		Jun. 30, 2012		Mar. 31, 2012		Dec. 31, 2011		Sep. 30, 2011		Jun. 30, 2011		Mar. 31, 2011		Dec. 31, 2012		Dec. 31, 2011		Dec. 31, 2010
Quarterly Financial Information [Line Items]
Sales and other operating revenues	$ 7,385,000		$ 7,130,600		$ 7,146,800		$ 6,953,900		$ 6,800,900		$ 7,194,400		$ 7,351,100		$ 6,236,000		$ 28,616,331		$ 27,582,423	[1]	$ 20,092,836	[1]
Income from continuing operations before income taxes	262,700		406,700		488,000		465,600		86,500		526,700		486,200		393,200		1,622,982		1,492,644	[1]	1,325,652	[1]
Income (loss) from continuing operations	162,400		228,900		291,300		281,500		(117,900)		347,300		270,600		229,500		964,046		729,471	[1]	749,080	[1]
Net income	$ 158,700		$ 226,700		$ 295,400		$ 290,100		$ (113,900)		$ 406,100		$ 311,600		$ 268,900		$ 970,876		$ 872,702	[1]	$ 798,081	[1]
Income (loss) from continuing operations per Common share
Basic	$ 0.84		$ 1.18		$ 1.50		$ 1.45		$ (0.61)		$ 1.80		$ 1.40		$ 1.19		$ 4.97		$ 3.77	[1]	$ 3.90	[1]
Diluted	$ 0.84		$ 1.17		$ 1.50		$ 1.44		$ (0.61)		$ 1.79		$ 1.39		$ 1.18		$ 4.95		$ 3.75	[1]	$ 3.88	[1]
Net income (loss) per Common share
Basic	$ 0.82		$ 1.17		$ 1.52		$ 1.50		$ (0.59)		$ 2.10		$ 1.61		$ 1.39		$ 5.01		$ 4.51	[1]	$ 4.16	[1]
Diluted	$ 0.82		$ 1.16		$ 1.52		$ 1.49		$ (0.59)		$ 2.09		$ 1.60		$ 1.38		$ 4.99		$ 4.49	[1]	$ 4.13	[1]
Cash dividend per Common share	$ 2.8125	[2]	$ 0.3125		$ 0.2750		$ 0.2750		$ 0.275		$ 0.275		$ 0.275		$ 0.275		$ 3.6750	[2]	$ 1.100
Market price of Common Stock
High	$ 63.74	[3]	$ 56.24	[3]	$ 57.12	[3]	$ 64.76	[3]	$ 58.67	[3]	$ 69.71	[3]	$ 77.48	[3]	$ 76.11	[3]	$ 64.76	[3]	$ 77.48	[3]
Low	$ 54.97	[3]	$ 48.80	[3]	$ 43.65	[3]	$ 55.82	[3]	$ 42.10	[3]	$ 44.05	[3]	$ 62.53	[3]	$ 65.74	[3]	$ 43.65	[3]	$ 42.10	[3]

[1] Reclassified to conform to current presentation.

[2] Includes special dividend of $2.50 per Common share paid on December 3, 2012.

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