Schedule Of Details Supporting Computation Of Earnings Per Share (Detail) (USD $) In Millions, except Share data in Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]
Net income available for common stockholders	$ 426	$ 445	$ 1,030	$ 1,220
Weighted average outstanding shares of common stock used to compute basic earnings per common share	160,639	164,121	162,391	166,138
Shares used to compute diluted earnings per common share	162,418	166,580	164,382	168,558
Basic earnings per common share	$ 2.65	$ 2.71	$ 6.34	$ 7.34
Diluted earnings per common share	$ 2.62	$ 2.67	$ 6.27	$ 7.24
Number of antidilutive stock options and restricted stock excluded from computation	758	168	799	1,017
Employee Stock Options
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]
Dilutive effect of employee stock options and restricted stock	431	895	629	962
Restricted Stock
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]
Dilutive effect of employee stock options and restricted stock	1,348	1,564	1,362	1,458