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	$ 412	412			412
Other comprehensive loss		32				32
Dividends		(448)			(448)
Shares issued:
Exercise of stock options (shares)			77,401
Exercise of stock options		3		3
Restricted stock awards (shares)			165,513
Other benefit plans (shares)			46,287
Other benefit plans		6		6
Dividend reinvestment plan (shares)			12,463
Dividend reinvestment plan		2		2
Stock-based compensation expense		9		9
Shares acquired and retired (shares)			(574,720)
Shares acquired and retired		(67)		(10)	(57)
Shares exchanged — benefit plans (shares)			(56,436)
Shares exchanged — benefit plans		(8)		(1)	(7)
Forfeitures of restricted stock (shares)			(15,986)
Ending Balance (shares) at Jun. 30, 2023			84,858,528
Ending Balance at Jun. 30, 2023		3,993		1,462	3,042	(511)
Beginning Balance (shares) at Mar. 31, 2023			85,171,658
Beginning Balance at Mar. 31, 2023		3,941		1,459	2,933	(451)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net earnings	$ 200	200			200
Other comprehensive loss		(60)				(60)
Dividends		(54)			(54)
Shares issued:
Exercise of stock options (shares)			13,062
Exercise of stock options		0		0
Restricted stock awards (shares)			18,344
Other benefit plans (shares)			33,988
Other benefit plans		4		4
Dividend reinvestment plan (shares)			1,552
Dividend reinvestment plan		1		1
Stock-based compensation expense		4		4
Shares acquired and retired (shares)			(374,958)
Shares acquired and retired		(43)		(6)	(37)
Shares exchanged — benefit plans (shares)			(1,054)
Shares exchanged — benefit plans		0		0	0
Forfeitures of restricted stock (shares)			(4,064)
Ending Balance (shares) at Jun. 30, 2023			84,858,528
Ending Balance at Jun. 30, 2023		3,993		1,462	3,042	(511)
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	$ 451	451			451
Other comprehensive loss		(12)				(12)
Dividends		(328)			(328)
Shares issued:
Exercise of stock options (shares)			96,134
Exercise of stock options		4		4
Restricted stock awards (shares)			157,681
Other benefit plans (shares)			51,161
Other benefit plans		7		7
Dividend reinvestment plan (shares)			10,068
Dividend reinvestment plan		1		1
Stock-based compensation expense		9		9
Shares acquired and retired (shares)			0
Shares acquired and retired		0		0	0
Shares exchanged — benefit plans (shares)			(47,891)
Shares exchanged — benefit plans		(6)		(1)	(5)
Forfeitures of restricted stock (shares)			(5,693)
Ending Balance (shares) at Jun. 30, 2024	83,897,267		83,897,267
Ending Balance at Jun. 30, 2024		4,384		1,476	3,239	(331)
Beginning Balance (shares) at Mar. 31, 2024			83,857,354
Beginning Balance at Mar. 31, 2024		4,240		1,466	3,089	(315)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net earnings	$ 209	209			209
Other comprehensive loss		(16)				(16)
Dividends		(59)			(59)
Shares issued:
Exercise of stock options (shares)			3,283
Restricted stock awards (shares)			0
Other benefit plans (shares)			35,357
Other benefit plans		5		5
Dividend reinvestment plan (shares)			1,815
Dividend reinvestment plan		0		0
Stock-based compensation expense		5		5
Shares acquired and retired (shares)			0
Shares acquired and retired		0		0	0
Shares exchanged — benefit plans (shares)			(21)
Shares exchanged — benefit plans				0	0
Forfeitures of restricted stock (shares)			(521)
Ending Balance (shares) at Jun. 30, 2024	83,897,267		83,897,267
Ending Balance at Jun. 30, 2024		$ 4,384		$ 1,476	$ 3,239	$ (331)