Consolidated Statement of Changes in Equity (Unaudited) - USD ($) $ in Millions	Total	Total	Common Shares	Common Stock and Capital Surplus	Retained Earnings	Accumulated Other Comp. Income (Loss)
Beginning Balance (shares) at Dec. 31, 2022			85,204,006
Beginning Balance at Dec. 31, 2022		$ 4,052		$ 1,453	$ 3,142	$ (543)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net earnings	$ 212	212			212
Other comprehensive income		92				92
Dividends		(394)			(394)
Shares issued:
Exercise of stock options (shares)			64,339
Exercise of stock options		3		3
Restricted stock awards (shares)			147,169
Other benefit plans (shares)			12,299
Other benefit plans		2		2
Dividend reinvestment plan (shares)			10,911
Dividend reinvestment plan		1		1
Stock-based compensation expense		5		5
Shares acquired and retired (shares)			(199,762)
Shares acquired and retired		(24)		(4)	(20)
Shares exchanged — benefit plans (shares)			(55,382)
Shares exchanged — benefit plans		(8)		(1)	(7)
Forfeitures of restricted stock (shares)			(11,922)
Ending Balance (shares) at Mar. 31, 2023			85,171,658
Ending Balance at Mar. 31, 2023		3,941		1,459	2,933	(451)
Beginning Balance (shares) at Dec. 31, 2023	83,635,807		83,635,807
Beginning Balance at Dec. 31, 2023		4,258		1,456	3,121	(319)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net earnings	$ 242	242			242
Other comprehensive income		4				4
Dividends		(269)			(269)
Shares issued:
Exercise of stock options (shares)			92,851
Exercise of stock options		4		4
Restricted stock awards (shares)			157,681
Other benefit plans (shares)			15,804
Other benefit plans		2		2
Dividend reinvestment plan (shares)			8,253
Dividend reinvestment plan		1		1
Stock-based compensation expense		4		4
Shares acquired and retired (shares)			0
Shares acquired and retired		0		0	0
Shares exchanged — benefit plans (shares)			(47,870)
Shares exchanged — benefit plans		(6)		(1)	(5)
Forfeitures of restricted stock (shares)			(5,172)
Ending Balance (shares) at Mar. 31, 2024	83,857,354		83,857,354
Ending Balance at Mar. 31, 2024		$ 4,240		$ 1,466	$ 3,089	$ (315)