Capital Stock - Additional Information (Detail) (USD $)	1 Months Ended	3 Months Ended		6 Months Ended
	May 31, 2013	Mar. 31, 2014	Mar. 31, 2013	Dec. 31, 2013
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Options and restricted stock, anti-dilutive		5,800,000	5,700,000
Common stock dividend paid		$ 79,000,000	$ 67,000,000
Increase in quarterly cash dividend		25.00%
Dividend, Common Stock		$ 0.25	$ 0.20
Dividend, Preferred Stock, Cash			19,000,000
Common stock share purchase, shares	30,000,000
Common stock share purchase, value	$ 2,000,000,000
Common stock share repurchase, shares		5,919,083		11,221,919
Common stock share repurchase, per share		$ 81.88		$ 88.88
Subsequent Event [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common stock share repurchase, shares		5,951,031
Common stock share repurchase, per share		$ 85.14