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, 2021			84,920,965
Beginning Balance at Dec. 31, 2021		$ 5,012		$ 1,415	$ 3,478	$ 119
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net earnings	$ 622	622			622
Other comprehensive loss		(721)				(721)
Dividends		(993)			(993)
Shares issued:
Exercise of stock options (shares)			138,498
Exercise of stock options		5		5
Restricted stock awards (shares)			151,080
Other benefit plans (shares)			54,171
Other benefit plans		7		7
Dividend reinvestment plan (shares)			27,518
Dividend reinvestment plan		4		4
Stock-based compensation expense		14		14
Shares acquired and retired (shares)			(80,701)
Shares acquired and retired		(10)		(1)	(9)
Shares exchanged — benefit plans (shares)			(57,195)
Shares exchanged — benefit plans		(8)		(1)	(7)
Forfeitures of restricted stock (shares)			(13,815)
Ending Balance (shares) at Sep. 30, 2022			85,140,521
Ending Balance at Sep. 30, 2022		3,932		1,443	3,091	(602)
Beginning Balance (shares) at Jun. 30, 2022			85,154,263
Beginning Balance at Jun. 30, 2022		4,067		1,436	2,979	(348)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net earnings	$ 165	165			165
Other comprehensive loss		(254)				(254)
Dividends		(48)			(48)
Shares issued:
Exercise of stock options (shares)			14,553
Exercise of stock options		0		0
Restricted stock awards (shares)			0
Other benefit plans (shares)			19,220
Other benefit plans		2		2
Dividend reinvestment plan (shares)			1,328
Dividend reinvestment plan		1		1
Stock-based compensation expense		4		4
Shares acquired and retired (shares)			(45,500)
Shares acquired and retired		(5)		0	(5)
Shares exchanged — benefit plans (shares)			(886)
Shares exchanged — benefit plans		0		0	0
Forfeitures of restricted stock (shares)			(2,457)
Ending Balance (shares) at Sep. 30, 2022			85,140,521
Ending Balance at Sep. 30, 2022		3,932		1,443	3,091	(602)
Beginning Balance (shares) at Dec. 31, 2022	85,204,006		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 loss		(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		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 loss		(59)				(59)
Dividends		(52)			(52)
Shares issued:
Exercise of stock options (shares)			6,230
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		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
Forfeitures of restricted stock (shares)			(652)
Ending Balance (shares) at Sep. 30, 2023	84,135,710		84,135,710
Ending Balance at Sep. 30, 2023		$ 3,981		$ 1,456	$ 3,095	$ (570)