Net Income Per Share - Additional Information (Detail) - USD ($) $ / shares in Units, $ in Millions			3 Months Ended		9 Months Ended
	Sep. 15, 2021	Sep. 17, 2018	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020	Dec. 31, 2020
Earnings Per Share [Abstract]
Dividends declared per share, in dollars per share			$ 0.79	$ 0.77	$ 2.33	$ 2.27
Tangible equity units issued		16,500,000
Tangible equity units proceeds		$ 800
Shares issued during period	5,460,031
Price for basic share (usd per share)					0.330911	0.313400
Tangible Equity Units, Price for Shares Diluted					0.330911	0.383900
Difference between basic and diluted net income per share, in dollars per share			0.01	$ 0.01	0.01	$ 0.03
Common stock, par value, in dollars per share			$ 0.125		$ 0.125		$ 0.125