Debt (Narrative) (Details) - USD ($) $ in Millions		3 Months Ended	6 Months Ended
	Mar. 15, 2023	Jun. 30, 2023	Jun. 30, 2023	Jun. 30, 2022	Feb. 08, 2023	Jan. 17, 2023	Dec. 31, 2022
Debt Instrument [Line Items]
Repayments of Long-term Debt			$ 1,908	$ 943
Short-term borrowings		$ 265	$ 265				$ 265
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 June 30, 2023, our debt-to-capital ratio, as defined and calculated under the 5-Year Facility, was 39.6%. We do not believe the restrictions contained in our 5-Year Facility covenants materially affect our financial or operating flexibility. As of June 30, 2023, we were in compliance with all of our debt covenants under the 5-Year Facility.
Maximum borrowing capacity		4,000	$ 4,000
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		175	175				265
Surplus Notes [Member]
Debt Instrument [Line Items]
Long-term Debt		25	25				25
Senior Unsecured Notes [Member]
Debt Instrument [Line Items]
Long-term Debt		24,834	24,834				23,761
Senior Unsecured Notes [Member] | Four Point Nine Zero Zero Percent Due Two Thousand Twenty Six
Debt Instrument [Line Items]
Debt instrument interest rate					4.90%
Debt Instrument, Face Amount					$ 500
Senior Unsecured Notes [Member] | Four Point Seven Five Zero Percent Due Two Thousand Thirty Three
Debt Instrument [Line Items]
Debt instrument interest rate					4.75%
Debt Instrument, Face Amount					$ 1,000
Senior Unsecured Notes [Member] | Five Point One Two Five Percent Due Two Thousand Fifty Three
Debt Instrument [Line Items]
Debt instrument interest rate					5.125%
Debt Instrument, Face Amount					$ 1,100
Senior Unsecured Notes [Member] | Three Point Three Zero Zero Percent Due Two Thousand Twenty Three
Debt Instrument [Line Items]
Debt instruments, repurchased face amount						$ 1,000
Debt instrument interest rate						3.30%
Senior Unsecured Notes [Member] | Zero Point Four Five Zero Percent Due Two Thousand Twenty Three
Debt Instrument [Line Items]
Debt instruments, repurchased face amount	$ 500
Debt instrument interest rate	0.45%
Commercial Paper
Debt Instrument [Line Items]
Commercial paper authorized		4,000	4,000
Commercial paper		90	$ 90				$ 0
Senior Convertible Debenture [Member] | Two Point Seven Five Zero Percent Due Two Thousand Forty Two
Debt Instrument [Line Items]
Debt Conversion Debt Principal Amount		59
Repayments of Long-term Debt	$ 5	$ 404
Debt Instrument, Redemption Price, Percentage of Principal Amount Redeemed	100.00%