Schedule Of Details Supporting Computation Of Earnings Per Share (Detail) (USD $) In Millions, except Share data in Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2012	Jun. 30, 2011	Jun. 30, 2012	Jun. 30, 2011
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]
Net income available for common stockholders	$ 356	$ 460	$ 604	$ 775
Weighted average outstanding shares of common stock used to compute basic earnings per common share	162,816	167,021	163,267	167,146
Shares used to compute diluted earnings per common share	164,639	169,560	165,363	169,547
Basic earnings per common share	$ 2.19	$ 2.76	$ 3.70	$ 4.64
Diluted earnings per common share	$ 2.16	$ 2.71	$ 3.65	$ 4.57
Number of antidilutive stock options and restricted stock excluded from computation	562	139	819	1,441
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	572	1,073	727	996
Restricted Stock
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]
Dilutive effect of employee stock options and restricted stock	1,251	1,466	1,369	1,405