Capital Stock - Additional Information (Detail) - USD ($)	12 Months Ended			111 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2015	Oct. 27, 2006
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	$ 0.4732	$ 0.44	$ 0.4
Share repurchase program					$ 1,000,000,000
Shares purchased under share repurchase program	2,000,000	1,100,000	3,100,000	18,400,000
Cost of shares repurchased under share repurchase program	$ 80,000,000	$ 50,000,000	$ 85,200,000	$ 759,300,000
Number of share repurchased under settlement of employee tax withholding obligations	100,000	200,000	100,000
Shares repurchased aggregate value under settlement of employee tax withholding obligations	$ 4,000,000	$ 10,200,000	$ 2,700,000
Common Stock held in treasury account	15,000,000	13,300,000		15,000,000
Common Stock [Member]
Class of Stock [Line Items]
Shares purchased under share repurchase program	2,100,000	1,400,000	3,200,000
Cost of shares repurchased under share repurchase program	$ 2,100,000	$ 1,400,000	$ 3,200,000
Activity from stock incentive plans	600,000	1,400,000	2,300,000