Schedule of Details Supporting Computation of Earnings Per Share (Detail) (USD $) In Millions, except Share data in Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2014	Mar. 31, 2013
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]
Net income available for common stockholders	$ 368	$ 473
Weighted average outstanding shares of common stock used to compute basic earnings per common share	155,091	158,917
Shares used to compute diluted earnings per common share	156,647	160,403
Basic earnings per common share	$ 2.37	$ 2.97
Diluted earnings per common share	$ 2.35	$ 2.95
Number of antidilutive stock options and restricted stock excluded from computation	972	1,683
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	268	384
Restricted Stock
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]
Dilutive effect of employee stock options and restricted stock	1,288	1,102