Schedule II. Condensed Financial Information of Registrant (Parent Company) (Schedule of Condensed Financial Information of Registrant, Balance Sheets) (Details) - USD ($) $ / shares in Units, $ in Millions	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Assets
Cash	$ 472	$ 345
Other assets	2,591	2,534
Total assets	66,492	64,711
Liabilities
Short-term debt	0	550
Long-term debt	2,973	2,481
Other liabilities	2,996	2,897
Total liabilities	55,979	54,818
Stockholders' Equity
Common stock ($2.50 par value; 500,000,000 shares authorized; 273,040,243 shares issued; 270,844,681 and 270,881,457 shares outstanding)	683	683
Additional paid-in capital	2,229	2,221
Retained earnings	9,686	9,755
Accumulated other comprehensive loss	(1,991)	(2,672)
Treasury stock (2,195,562 and 2,158,786 shares), at cost	(94)	(94)
Total stockholders’ equity	10,513	9,893	$ 8,548
Total liabilities and stockholders' equity	$ 66,492	$ 64,711
Balance Sheet Parenthetical
Common stock, par value (in usd per share)	$ 2.50	$ 2.50
Common stock, shares authorized (in shares	500,000,000	500,000,000
Common stock, shares issued (in shares)	273,040,243	273,040,243
Common stock, shares outstanding (in shares)	270,844,681	270,881,457
Treasury stock, shares (in shares)	2,195,562	2,158,786
Related Party
Assets
Other assets	$ 0	$ 23
Liabilities
Other liabilities	47	28
Parent Company
Assets
Investment in subsidiaries	12,684	11,948
Cash	1	1
Short-term investments	846	1,009
Total assets	13,536	12,963
Liabilities
Short-term debt	0	550
Long-term debt	2,973	2,481
Other liabilities	50	39
Total liabilities	3,023	3,070
Stockholders' Equity
Common stock ($2.50 par value; 500,000,000 shares authorized; 273,040,243 shares issued; 270,844,681 and 270,881,457 shares outstanding)	683	683
Additional paid-in capital	2,229	2,221
Retained earnings	9,686	9,755
Accumulated other comprehensive loss	(1,991)	(2,672)
Treasury stock (2,195,562 and 2,158,786 shares), at cost	(94)	(94)
Total stockholders’ equity	10,513	9,893
Total liabilities and stockholders' equity	13,536	12,963
Parent Company \| Related Party
Assets
Other assets	4	4
Parent Company \| Nonrelated Party
Assets
Other assets	$ 1	$ 1

Schedule II. Condensed Financial Information of Registrant (Parent Company) (Schedule of Condensed Financial Information of Registrant, Balance Sheets) (Details) - USD ($)
$ / shares in Units, $ in Millions

Dec. 31, 2024

Dec. 31, 2023

Dec. 31, 2022

Assets

Cash

$ 472

$ 345

Other assets

2,591

2,534

Total assets

66,492