Capital Structure - Narrative (Details)		12 Months Ended
	May 15, 2024 USD ($)	Dec. 31, 2024 USD ($) director $ / shares shares	Dec. 31, 2023 USD ($) $ / shares shares	Dec. 31, 2022 USD ($)	Jun. 24, 2024 USD ($)
Class of Stock [Line Items]
Long-term debt		$ 8,085,000,000	$ 7,942,000,000
Additional borrowing capacity under credit facility increase provision		$ 500,000,000
Maximum debt to capital ratio allowed under credit facility covenant (as a percent)		37.50%
Credit facility, amount outstanding		$ 0	0
Interest paid on debt		395,000,000	355,000,000	$ 323,000,000
Other liabilities and accrued expenses		$ 215,000,000	$ 209,000,000
Common stock
Common stock, shares, issued (in shares) | shares		900,000,000	900,000,000
Common stock, shares, outstanding (in shares) | shares		265,000,000	262,000,000
Treasury stock, shares (in shares) | shares		635,000,000	638,000,000
Reacquired shares (in shares) | shares		278,000
Average cost of reacquired shares (in dollars per share) | $ / shares		$ 174.03
Reissued net shares under equity incentive plans (in shares) | shares		2,000,000
Preferred stock
Preferred stock, par value (in dollars per share) | $ / shares		$ 1	$ 1
Subordinated Debentures Due After January 15, 2023
Class of Stock [Line Items]
Debt instrument, face amount		$ 500,000,000
Subordinated Debentures Due August 15, 2023
Class of Stock [Line Items]
Debt instrument, face amount		$ 800,000,000
Noncumulative Perpetual Preferred Stock
Preferred stock
Preferred stock, par value (in dollars per share) | $ / shares		$ 1.00
Preferred stock, shares liquidation preference (in dollars per share) | $ / shares		25,000
Preferred stock, redemption price (in dollars per share) | $ / shares		$ 25,000
Period after occurrence of certain tax and rating agency events in which redemption of debt in whole permissible		90 days
Maximum | Noncumulative Perpetual Preferred Stock
Preferred stock
Additional members of the board of directors | director		2
Preferred stock, redemption price (in dollars per share) | $ / shares		$ 25,500
Minimum | Noncumulative Perpetual Preferred Stock
Preferred stock
Preferred stock, redemption price (in dollars per share) | $ / shares		$ 25,000
Commercial Paper
Class of Stock [Line Items]
Commercial paper maximum borrowing capacity		$ 750,000,000
Amount of commercial paper outstanding		0	$ 0
Commercial Paper | Revolving Credit Facility
Class of Stock [Line Items]
Commercial paper maximum borrowing capacity		750,000,000
Senior Notes | Senior Notes Due 2024 at 6.75 Percent
Class of Stock [Line Items]
Repayments of senior debt	$ 350,000,000
Stated interest rate (as a percent)	6.75%
Senior Notes | 5.050% Senior Notes, due 2029
Class of Stock [Line Items]
Stated interest rate (as a percent)					5.05%
Debt instrument, face amount					$ 500,000,000
Subordinated Debentures
Class of Stock [Line Items]
Minimum principal outstanding amount for redemption of debt in whole or in part		25,000,000
Subordinated Debentures Due January 14, 2023
Class of Stock [Line Items]
Debt instrument, face amount		$ 500,000,000
Interest rate spread overSOFR (as a percent)		0.26161%
Subordinated Debentures Due January 14, 2023 | Secured Overnight Financing Rate (SOFR)
Class of Stock [Line Items]
Interest rate spread overSOFR (as a percent)		3.165%
Subordinated Debentures Due August 14, 2023
Class of Stock [Line Items]
Debt instrument, face amount		$ 800,000,000
Interest rate spread overSOFR (as a percent)		0.26161%
Subordinated Debentures Due August 14, 2023 | Secured Overnight Financing Rate (SOFR)
Class of Stock [Line Items]
Interest rate spread overSOFR (as a percent)		2.938%
6.500% Junior Subordinated Debentures, due 2067
Class of Stock [Line Items]
Stated interest rate (as a percent)		6.50%
Long-term debt		$ 500,000,000
6.500% Junior Subordinated Debentures, due 2067 | Secured Overnight Financing Rate (SOFR)
Class of Stock [Line Items]
Interest rate spread overSOFR (as a percent)		0.26161%
6.500% Junior Subordinated Debentures, due 2067 | London Interbank Offered Rate
Class of Stock [Line Items]
Interest rate spread overSOFR (as a percent)		2.12%
Debentures
Class of Stock [Line Items]
Maximum period for deferment of interest payment		10 years
Reserved common stock authorized and unissued for debentures obligations (in shares) | shares		75,000,000
Floating Rate Subordinated Debentures, due 2053
Class of Stock [Line Items]
Debt instrument, face amount		$ 800,000,000
7.45% Senior Notes, due 2019
Class of Stock [Line Items]
Threshold percentage of repurchase or redemption of outstanding principal debentures for non applicability of promises and covenants contained in the new RCC		10.00%
Period within which threshold percentage of outstanding principal of debentures is to be purchased for non applicability of promises and covenants contained in the new RCC		1 year
Specified period within which percentage of outstanding principal of debentures is to be purchased for non applicability of promises and covenants contained in the new RCC		10 years
7.45% Senior Notes, due 2019 | Maximum
Class of Stock [Line Items]
Percentage of repurchase or redemption of outstanding principal debentures within specified period for non applicability of promises and covenants contained in the new RCC		25.00%