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	$ 589	589			589
Other comprehensive income		(27)				(27)
Dividends		(500)			(500)
Shares issued:
Exercise of stock options (shares)			83,631
Exercise of stock options		3		3
Restricted stock awards (shares)			165,513
Other benefit plans (shares)			71,499
Other benefit plans		9		9
Dividend reinvestment plan (shares)			14,159
Dividend reinvestment plan		2		2
Stock-based compensation expense		14		14
Shares acquired and retired (shares)			(1,329,831)
Shares acquired and retired		(153)		(24)	(129)
Shares exchanged — benefit plans (shares)			(56,629)
Shares exchanged — benefit plans		(8)		(1)	(7)
Forfeitures of restricted stock (shares)			(16,638)
Ending Balance (shares) at Sep. 30, 2023			84,135,710
Ending Balance at Sep. 30, 2023		3,981		1,456	3,095	(570)
Beginning Balance (shares) at Jun. 30, 2023			84,858,528
Beginning Balance at Jun. 30, 2023		3,993		1,462	3,042	(511)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net earnings	$ 177	177			177
Other comprehensive income		(59)				(59)
Dividends		(52)			(52)
Shares issued:
Exercise of stock options (shares)			6,230
Exercise of stock options		0		0
Restricted stock awards (shares)			0
Other benefit plans (shares)			25,212
Other benefit plans		3		3
Dividend reinvestment plan (shares)			1,696
Dividend reinvestment plan		0
Stock-based compensation expense		5		5
Shares acquired and retired (shares)			(755,111)
Shares acquired and retired		(86)		(14)	(72)
Shares exchanged — benefit plans (shares)			(193)
Shares exchanged — benefit plans		0		0	0
Forfeitures of restricted stock (shares)			(652)
Ending Balance (shares) at Sep. 30, 2023			84,135,710
Ending Balance at Sep. 30, 2023		3,981		1,456	3,095	(570)
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	$ 632	632			632
Other comprehensive income		183				183
Dividends		(387)			(387)
Shares issued:
Exercise of stock options (shares)			110,631
Exercise of stock options		5		5
Restricted stock awards (shares)			157,681
Other benefit plans (shares)			72,074
Other benefit plans		9		9
Dividend reinvestment plan (shares)			11,910
Dividend reinvestment plan		2		2
Stock-based compensation expense		13		13
Shares acquired and retired (shares)			0
Shares acquired and retired		0		0	0
Shares exchanged — benefit plans (shares)			(53,362)
Shares exchanged — benefit plans		(7)		(1)	(6)
Forfeitures of restricted stock (shares)			(11,295)
Ending Balance (shares) at Sep. 30, 2024	83,923,446		83,923,446
Ending Balance at Sep. 30, 2024		4,708		1,484	3,360	(136)
Beginning Balance (shares) at Jun. 30, 2024			83,897,267
Beginning Balance at Jun. 30, 2024		4,384		1,476	3,239	(331)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net earnings	$ 181	181			181
Other comprehensive income		195				195
Dividends		(59)			(59)
Shares issued:
Exercise of stock options (shares)			14,497
Exercise of stock options		1		1
Restricted stock awards (shares)			0
Other benefit plans (shares)			20,913
Other benefit plans		2		2
Dividend reinvestment plan (shares)			1,842
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)			(5,471)
Shares exchanged — benefit plans		(1)		0	(1)
Forfeitures of restricted stock (shares)			(5,602)
Ending Balance (shares) at Sep. 30, 2024	83,923,446		83,923,446
Ending Balance at Sep. 30, 2024		$ 4,708		$ 1,484	$ 3,360	$ (136)