Capital Stock - Additional Information (Detail) (USD $)	1 Months Ended	12 Months Ended			99 Months Ended
	Oct. 27, 2006	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2014
Class of Stock [Line Items]
Aggregate common stock and preferred stock authorized		300,000,000			300,000,000
Common stock, authorized		250,000,000	250,000,000		250,000,000
Common stock, par value		$ 1	$ 1.00		$ 1
Preferred Stock, authorized		50,000,000			50,000,000
Preferred Stock, outstanding		0	0		0
Dividends declared per common share		$ 0.44	$ 0.40	$ 0.364
Term of repurchase program	3 years
Share repurchase program	$ 1,000,000,000
Shares purchased under share repurchase program		1,100,000	3,100,000		16,400,000
Cost of shares repurchased under share repurchase program		50,000,000	85,200,000		679,300,000
Number of share repurchased under settlement of employee tax withholding obligations		200,000	100,000	100,000
Shares repurchased aggregate value under settlement of employee tax withholding obligations		10,200,000	2,700,000	3,400,000
Common Stock held in treasury account		13,300,000	13,000,000		13,300,000
Common Stock [Member]
Class of Stock [Line Items]
Shares purchased under share repurchase program		1,400,000	3,200,000	5,200,000
Cost of shares repurchased under share repurchase program		$ 1,400,000	$ 3,200,000	$ 5,200,000
Issuance of shares from treasury account related to equity compensation arrangements		1,400,000	2,300,000	4,000,000