Capital Stock - Additional Information (Detail) - USD ($)	12 Months Ended			159 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2019	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	$ 0.588	$ 0.536	$ 0.512
Share repurchase program					$ 1,000,000,000
Shares repurchased	500,000	1,000,000.0	800,000	22,700,000
Cost of shares repurchased	$ 41,400,000	$ 56,100,000	$ 32,900,000	$ 938,100,000
Common Stock [Member]
Class of Stock [Line Items]
Shares repurchased	800,000	1,100,000	900,000
Cost of shares repurchased	$ 800,000	$ 1,100,000	$ 900,000
Share Repurchase Program [Member]
Class of Stock [Line Items]
Cost of shares repurchased	$ 28,700,000	$ 50,000,000.0	$ 30,000,000.0
Settlement of Tax Withholding on Employee Equity Compensation [Member]
Class of Stock [Line Items]
Shares repurchased	300,000	100,000	100,000
Cost of shares repurchased	$ 12,700,000	$ 6,100,000	$ 2,900,000