10-K Debt (Narrative) (Details)								3 Months Ended		9 Months Ended		12 Months Ended
	Apr. 18, 2023 USD ($)	Mar. 15, 2023 USD ($)	Feb. 13, 2023	Oct. 15, 2022	Apr. 18, 2022 USD ($)	May 15, 2021 USD ($)	Oct. 02, 2012 $ / shares	Sep. 30, 2023 USD ($)	Mar. 31, 2023 USD ($)	Sep. 30, 2023 USD ($)	Sep. 30, 2022 USD ($)	Dec. 31, 2022 USD ($) $ / shares	Dec. 31, 2021 USD ($)	Dec. 31, 2020 USD ($)	Jun. 30, 2023 USD ($)	Feb. 08, 2023 USD ($)	Dec. 01, 2022 USD ($)	Nov. 04, 2022 USD ($)	Jul. 31, 2022 USD ($)	Jun. 30, 2022 USD ($)	May 16, 2022 USD ($)	Apr. 29, 2022 USD ($)	Mar. 31, 2022 USD ($)	Jan. 01, 2022 USD ($)	Mar. 17, 2021 USD ($)	Nov. 23, 2020 USD ($)	Aug. 17, 2020 USD ($)	May 05, 2020 USD ($)	Dec. 31, 2019 USD ($)	Sep. 09, 2019 USD ($)	Oct. 09, 2012 USD ($)
Debt Instrument [Line Items]
Debt Instrument, Face Amount												$ 63,000,000
(Loss) gain on extinguishment of debt												$ 0	$ (21,000,000)	$ (36,000,000)
Conversion rate (shares of common stock per $1,000 of principal)												14.3238
Effective conversion price (per $1,000 of principal amount) per share | $ / shares												$ 69.8139
Repayments of Long-term Debt										$ 1,908,000,000	$ 982,000,000	$ 1,899,000,000	1,068,000,000	1,932,000,000
Long-term Debt												23,849,000,000	22,756,000,000
Total Shareholders' Balance, beginning								$ 38,423,000,000		38,423,000,000	36,055,000,000	36,243,000,000	36,095,000,000
Interest Paid, Including Capitalized Interest, Operating and Investing Activities												878,000,000	822,000,000	794,000,000
Long-Term Debt, Maturity, Year One												1,500,000,000
Long-Term Debt, Maturity, Year Two												1,647,000,000
Long-Term Debt, Maturity, Year Three												1,650,000,000
Long-Term Debt, Maturity, Year Four												746,000,000
Long-Term Debt, Maturity, Year Five												1,592,000,000
Long-Term Debt, Maturity, after Year Five												16,714,000,000
Retained Earnings [Member]
Debt Instrument [Line Items]
Total Shareholders' Balance, beginning								32,103,000,000	$ 30,707,000,000	32,103,000,000	$ 29,611,000,000	29,647,000,000	27,142,000,000	23,802,000,000	$ 31,608,000,000					$ 28,847,000,000			$ 28,096,000,000						$ 22,538,000,000
Cumulative Effect, Period of Adoption, Adjustment | Accounting Standards Update 2020-06 [Member] | Retained Earnings [Member]
Debt Instrument [Line Items]
Long-term Debt													31,000,000											$ 31,000,000
Deferred Tax and Other Liabilities, Noncurrent													(8,000,000)											(8,000,000)
Total Shareholders' Balance, beginning													(23,000,000)											$ (23,000,000)
2021 364-Day Facility
Debt Instrument [Line Items]
Line of Credit Facility, Description					Also on April 18, 2022, concurrently with the amendment and restatement of the 5-Year Facility, we terminated our 364-day senior revolving credit facility that provided for credit in the amount of $1,000, which was scheduled to mature in June 2022
Senior Unsecured Notes [Member]
Debt Instrument [Line Items]
Long-term Debt								24,819,000,000		24,819,000,000		23,761,000,000
Other senior unsecured notes
Debt Instrument [Line Items]
Extinguishment of Debt, Amount													52,000,000	79,000,000
Remarketable subordinated notes tendered, cash payment													67,000,000	109,000,000
(Loss) gain on extinguishment of debt													15,000,000	(30,000,000)
Commercial Paper
Debt Instrument [Line Items]
Commercial paper authorized								4,000,000,000		4,000,000,000		4,000,000,000	3,500,000,000						$ 4,000,000,000
Commercial paper												$ 0	$ 300,000,000
Long-Term Debt, Weighted Average Interest Rate, at Point in Time													0.15%
Four Point Nine Zero Zero Percent Due Two Thousand Twenty Six | Senior Unsecured Notes [Member]
Debt Instrument [Line Items]
Debt instrument interest rate																4.90%
Debt Instrument, Face Amount																$ 500,000,000
Four Point Nine Zero Zero Percent Due Two Thousand Twenty Six | Senior Unsecured Notes [Member] | Subsequent Event [Member]
Debt Instrument [Line Items]
Debt instrument interest rate																4.90%
Debt Instrument, Face Amount																$ 500,000,000
Four Point Seven Five Zero Percent Due Two Thousand Thirty Three | Senior Unsecured Notes [Member]
Debt Instrument [Line Items]
Debt instrument interest rate																4.75%
Debt Instrument, Face Amount																$ 1,000,000,000
Four Point Seven Five Zero Percent Due Two Thousand Thirty Three | Senior Unsecured Notes [Member] | Subsequent Event [Member]
Debt Instrument [Line Items]
Debt instrument interest rate																4.75%
Debt Instrument, Face Amount																$ 1,000,000,000
Five Point One Two Five Percent Due Two Thousand Fifty Three | Senior Unsecured Notes [Member]
Debt Instrument [Line Items]
Debt instrument interest rate																5.125%
Debt Instrument, Face Amount																$ 1,100,000,000
Five Point One Two Five Percent Due Two Thousand Fifty Three | Senior Unsecured Notes [Member] | Subsequent Event [Member]
Debt Instrument [Line Items]
Debt instrument interest rate																5.125%
Debt Instrument, Face Amount																$ 1,100,000,000
Two Point Nine Five Zero Percent Due Two Thousand Twenty Two | Senior Unsecured Notes [Member]
Debt Instrument [Line Items]
Debt instrument interest rate												2.95%					2.95%
Debt instruments, repurchased face amount																	$ 750,000,000
Long-term Debt												$ 0	$ 749,000,000
Five Point Three Five Zero Percent Due Two Thousand Twenty Five | Senior Unsecured Notes [Member]
Debt Instrument [Line Items]
Debt instrument interest rate												5.35%						5.35%
Debt Instrument, Face Amount																		$ 400,000,000
Long-term Debt												$ 398,000,000	0
Five Point Five Zero Zero Percent Due Two Thousand Thirty Two | Senior Unsecured Notes [Member]
Debt Instrument [Line Items]
Debt instrument interest rate												5.50%						5.50%
Debt Instrument, Face Amount																		$ 650,000,000
Long-term Debt												$ 644,000,000	0
Six Point One Zero Zero Percent Due Two Thousand Fifty Two | Senior Unsecured Notes [Member]
Debt Instrument [Line Items]
Debt instrument interest rate												6.10%						6.10%
Debt Instrument, Face Amount																		$ 750,000,000
Long-term Debt												$ 741,000,000	0
Three Point One Two Five Percent Due Two Thousand Twenty Two | Senior Unsecured Notes [Member]
Debt Instrument [Line Items]
Debt instrument interest rate												3.125%									3.125%
Debt instruments, repurchased face amount																					$ 850,000,000
Long-term Debt												$ 0	850,000,000
Four Point One Zero Percent Due Two Thousand Thirty Two | Senior Unsecured Notes [Member]
Debt Instrument [Line Items]
Debt instrument interest rate												4.10%										4.10%
Debt Instrument, Face Amount																						$ 600,000,000
Long-term Debt												$ 595,000,000	0
Four Point Five Five Zero Due Two Thousand Fifty Two | Senior Unsecured Notes [Member]
Debt Instrument [Line Items]
Debt instrument interest rate												4.55%										4.55%
Debt Instrument, Face Amount																						$ 700,000,000
Long-term Debt												$ 689,000,000	0
Three Point Seven Zero Zero Percent Due Two Thousand Twenty One | Senior Unsecured Notes [Member]
Debt Instrument [Line Items]
Debt instrument interest rate						3.70%
Debt, Redemption amount						$ 700,000,000
Debt Instrument, Redemption, Description						at a redemption price equal to 100% of the aggregate principal amount of the notes being redeemed, plus accrued and unpaid interest.
Zero Point Four Five Zero Percent Due Two Thousand Twenty Three | Senior Unsecured Notes [Member]
Debt Instrument [Line Items]
Debt instrument interest rate		0.45%										0.45%													0.45%
Debt Instrument, Face Amount																									$ 500,000,000
Debt instruments, repurchased face amount		$ 500,000,000
Long-term Debt												$ 500,000,000	499,000,000
One Point Five Zero Zero Percent Due Two Thousand Twenty Six | Senior Unsecured Notes [Member]
Debt Instrument [Line Items]
Debt instrument interest rate												1.50%													1.50%
Debt Instrument, Face Amount																									$ 750,000,000
Long-term Debt												$ 746,000,000	745,000,000
Two Point Five Five Zero Percent Due Two Thousand Thirty One | Senior Unsecured Notes [Member]
Debt Instrument [Line Items]
Debt instrument interest rate												2.55%													2.55%
Debt Instrument, Face Amount																									$ 1,000,000,000
Long-term Debt												$ 968,000,000	992,000,000
Three Point Six Zero Zero Percent Due Two Thousand Fifty One | Senior Unsecured Notes [Member]
Debt Instrument [Line Items]
Debt instrument interest rate												3.60%													3.60%
Debt Instrument, Face Amount																									$ 1,250,000,000
Long-term Debt												$ 1,233,000,000	1,232,000,000
Two Point Five Zero Zero Percent Due Two Thousand Twenty | Senior Unsecured Notes [Member]
Debt Instrument [Line Items]
Debt instrument interest rate																										2.50%
Debt instruments, repurchased face amount																										$ 900,000,000
Four Point Three Five Zero Percent Due Two Thousand Twenty | Senior Unsecured Notes [Member]
Debt Instrument [Line Items]
Debt instrument interest rate																											4.35%
Debt instruments, repurchased face amount																											$ 700,000,000
Two Point Three Seven Five Due Two Thousand Twenty Five | Senior Unsecured Notes [Member]
Debt Instrument [Line Items]
Debt instrument interest rate																												2.375%		2.375%
Debt Instrument, Face Amount																												$ 400,000,000		$ 850,000,000
Two Point Two Five Zero Percent Due Two Thousand Thirty | Senior Unsecured Notes [Member]
Debt Instrument [Line Items]
Debt instrument interest rate												2.25%																2.25%
Debt Instrument, Face Amount																												$ 1,100,000,000
Long-term Debt												$ 1,071,000,000	1,089,000,000
Three Point One Two Five Percent Due Two Thousand Fifty | Senior Unsecured Notes [Member]
Debt Instrument [Line Items]
Debt instrument interest rate												3.125%																3.125%
Debt Instrument, Face Amount																												$ 1,000,000,000
Long-term Debt												$ 988,000,000	987,000,000
Revolving Credit Facility [Member]
Debt Instrument [Line Items]
Line of Credit Facility, Maximum Borrowing Capacity								4,000,000,000		$ 4,000,000,000
Covenant description										Our ability to borrow under the 5-Year Facility is subject to compliance with certain covenants, including covenants requiring us to maintain a defined debt-to-capital ratio of not more than 60%, subject to increase in certain circumstances set forth in the credit agreement for the 5-Year Facility.
Covenant compliance										As of September 30, 2023, our debt-to-capital ratio, as defined and calculated under the 5-Year Facility, was 39.2%. We do not believe the restrictions contained in our 5-Year Facility covenants materially affect our financial or operating flexibility. As of September 30, 2023, we were in compliance with all of our debt covenants under the 5-Year Facility.
Revolving Credit Facility [Member] | 5-Year Facility
Debt Instrument [Line Items]
Line of Credit Facility, Maximum Borrowing Capacity	$ 2,500,000,000				$ 4,000,000,000
Revolving Credit Facility [Member] | 2021 364-Day Facility
Debt Instrument [Line Items]
Line of Credit Facility, Maximum Borrowing Capacity	$ 1,000,000,000
Two Point Seven Five Zero Percent Due Two Thousand Forty Two | Senior Convertible Debenture [Member]
Debt Instrument [Line Items]
Debt instrument interest rate												2.75%																			2.75%
Debt Instrument, Face Amount												$ 1,000																			$ 1,500,000,000
(Loss) gain on extinguishment of debt													(6,000,000)	(6,000,000)
Long-Term Debt, Contingent Payment of Principal or Interest				The Debentures also have a contingent interest feature that requires us to pay additional interest based on certain thresholds and for certain events, as defined in the Indenture, beginning on October 15, 2022. As of October 15, 2022, one of these events had occurred and contingent interest began accruing on the Debentures at a rate of 0.50% of the average trading price of a Debenture for the ten consecutive trading days ended October 14, 2022. Contingent interest will be payable on April 15, 2023, to holders of the Debentures as of the April 1, 2023 record date.
Debt Instrument, Convertible, Threshold Consecutive Trading Days												20
Number Of Consecutive Trading Days												30 days
Debt Instrument, Convertible, Threshold Percentage of Stock Price Trigger												130.00%
Measurement Period												10 days
Percent Conversion To Stock Price												98.00%
Debt Instrument, Convertible, Earliest Date												Apr. 15, 2042
Debt Instrument, Maturity Date												Oct. 15, 2042
Date Debentures Reedemable												Oct. 20, 2022
Conversion rate (shares of common stock per $1,000 of principal)							13.2319
Conversion Premium							25.00%
Share Price | $ / shares							$ 60.46					$ 512.97
Effective conversion price (per $1,000 of principal amount) per share | $ / shares							$ 75.575
Debt Conversion Debt Principal Amount									$ 59,000,000			$ 41,000,000	54,000,000	56,000,000
Repayments of Long-term Debt		$ 5,000,000						$ 404,000,000				299,000,000	302,000,000	222,000,000
Debt Instrument, Convertible, If-converted Value in Excess of Principal												402,000,000
Long-term Debt												63,000,000	72,000,000
Amoritization of bridge facility fees												2,000,000	4,000,000	6,000,000
Interest Expense, Debt, Excluding Amortization												2,000,000	3,000,000	5,000,000
Amortization of Debt Discount (Premium)												0	1,000,000	$ 1,000,000
Two Point Seven Five Zero Percent Due Two Thousand Forty Two | Senior Convertible Debenture [Member] | Subsequent Event [Member]
Debt Instrument [Line Items]
Debt Instrument, Redemption Period, End Date			Mar. 15, 2023
Debt Instrument, Redemption Price, Percentage			100.00%
Federal Home Loan Bank Advances [Member]
Debt Instrument [Line Items]
Short-term FHLB borrowings outstanding												$ 265,000,000	275,000,000
Debt instrument interest rate												4.24%
Subsidiary Credit Facilities [Member]
Debt Instrument [Line Items]
Line of Credit Facility, Maximum Borrowing Capacity												$ 200,000,000
Line of Credit Facility, Fair Value of Amount Outstanding												$ 0	$ 0
Revolving Credit Facility [Member]
Debt Instrument [Line Items]
Covenant description	Our ability to borrow under the 5-Year Facility is subject to compliance with certain covenants, including covenants requiring us to maintain a defined debt-to-capital ratio of not more than 60%, subject to increase in certain circumstances set forth in the credit agreement for the 5-Year Facility.
Covenant compliance	As of December 31, 2022, our debt-to-capital ratio, as defined and calculated under the 5-Year Facility, was 39.9%. We do not believe the restrictions contained in our 5-Year Facility covenants materially affect our financial or operating flexibility. As of December 31, 2022, we were in compliance with all of our debt covenants under the 5-Year Facility.