Debt (Narrative) (Details) - USD ($) $ in Millions		3 Months Ended		9 Months Ended
	Apr. 18, 2022	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2022	Sep. 30, 2021	Jun. 30, 2022	May 16, 2022	Apr. 29, 2022	Mar. 31, 2022	Dec. 31, 2021	Jun. 30, 2021	Mar. 31, 2021
Debt Instrument [Line Items]
Loss on extinguishment of debt		$ 0	$ 0	$ 0	$ 5
Commercial paper		675		675						$ 300
Stockholders' equity attributable to parent		35,991	35,808	35,991	35,808					36,060
Repayments of Long-term Debt				982	954
Short-term borrowings		265		265						275
Retained Earnings [Member]
Debt Instrument [Line Items]
Stockholders' equity attributable to parent		29,604	$ 26,700	$ 29,604	$ 26,700	$ 28,825			$ 28,058	27,088	$ 25,874	$ 24,793
Cumulative Effect, Period of Adoption, Adjustment | Accounting Standards Update 2020-06 [Member] | Retained Earnings [Member]
Debt Instrument [Line Items]
Long-term Debt										31
Deferred Tax and Other Liabilities, Noncurrent										(8)
Stockholders' equity attributable to parent										(23)
Senior 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 September 30, 2022, our debt-to-capital ratio, as defined and calculated under the 5-Year Facility, was 39.7%. We do not believe the restrictions contained in our 5-Year Facility covenants materially affect our financial or operating flexibility. As of September 30, 2022, we were in compliance with all of our debt covenants under the 5-Year Facility.
Convertible Debt [Member]
Debt Instrument [Line Items]
Debt Conversion Debt Principal Amount		4		$ 19
Repayments of Long-term Debt		25		132
Subsidiary Credit Facilities [Member]
Debt Instrument [Line Items]
Maximum borrowing capacity		200		200
Federal Home Loan Bank Advances [Member]
Debt Instrument [Line Items]
Federal Home Loan Bank, advances, short-term		265		265						275
Surplus Notes [Member]
Debt Instrument [Line Items]
Long-term Debt		25		25						25
Senior Unsecured Notes [Member]
Debt Instrument [Line Items]
Long-term Debt		22,722		22,722						22,359
Senior Unsecured Notes [Member] | Four Point One Zero Percent Due Two Thousand Thirty Two [Member]
Debt Instrument [Line Items]
Debt instrument interest rate								4.10%
Debt Instrument, Face Amount								$ 600
Senior Unsecured Notes [Member] | Four Point Five Five Zero Due Two Thousand Fifty Two [Member]
Debt Instrument [Line Items]
Debt instrument interest rate								4.55%
Debt Instrument, Face Amount								$ 700
Senior Unsecured Notes [Member] | Three Point One Two Five Percent Due Two Thousand Twenty Two [Member]
Debt Instrument [Line Items]
Debt instruments, repurchased face amount							$ 850
Debt instrument interest rate							3.125%
Commercial Paper Program
Debt Instrument [Line Items]
Commercial paper authorized		4,000		4,000		$ 3,500
Commercial paper		$ 675		$ 675						$ 300
2021 364-Day Facility [Member]
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
2021 364-Day Facility [Member] | Senior Revolving Credit Facility [Member]
Debt Instrument [Line Items]
Maximum borrowing capacity									1,000
5-Year Facility [Member] | Senior Revolving Credit Facility [Member]
Debt Instrument [Line Items]
Maximum borrowing capacity	$ 4,000								$ 2,500