10-K Accumulated Other Comprehensive Loss (Reconciliation Of The Components Of Accumulated Other Comprehensive Loss) (Details) - USD ($) $ in Millions	3 Months Ended						9 Months Ended		12 Months Ended
	Sep. 30, 2023	Jun. 30, 2023	Mar. 31, 2023	Sep. 30, 2022	Jun. 30, 2022	Mar. 31, 2022	Sep. 30, 2023	Sep. 30, 2022	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Change in net unrealized gains/losses on investments	$ (352)			$ (639)			$ (44)	$ (2,630)	$ (2,260)	$ (457)	$ 428
Change in net unrealized gains/losses on cash flow hedges	1			2			16	8	10	11	12
Change in net periodic pension and postretirement costs	2			7			7	23	(70)	123	(1)
Change in future policy benefits, net of tax	3			7			2	24	32	(7)	0
Foreign currency translation adjustment, net of tax	(4)			(7)			(2)	(15)	(13)	(9)	7
Accumulated Other Comprehensive Loss, Beginning Balance	(2,166)		$ (2,490)	(2,151)		$ (197)	(2,490)	(197)	(197)	150	(296)
Other Comprehensive Income (Loss), Net of Tax	(348)	$ (116)	442	(631)	$ (908)	(1,054)	(22)	(2,593)	(2,304)	(337)	446
Other comprehensive loss attributable to noncontrolling interests	2			3			0	11	11	2	0
Accumulated Other Comprehensive Loss, Ending Balance	(2,512)	(2,166)		(2,779)	(2,151)		(2,512)	(2,779)	(2,490)	(197)	150
Other Comprehensive Income (Loss), Tax									799	112	(154)
Other Comprehensive Income (Loss), Tax, Portion Attributable to Noncontrolling Interest	(1)			(1)			(1)	(4)	3	(1)	0
Previously Reported [Member]
Accumulated Other Comprehensive Loss, Beginning Balance										150
Accumulated Other Comprehensive Loss, Ending Balance											150
Revision of Prior Period, Accounting Standards Update, Adjustment [Member]
Accumulated Other Comprehensive Loss, Beginning Balance			13			(19)	13	(19)	(19)	(12)
Accumulated Other Comprehensive Loss, Ending Balance									13	(19)	(12)
Net unrealized investment (losses) gains
AOCI, Debt Securities, Beginning Balance			(1,768)			492	(1,768)	492	492	949	521
OCI, Debt Securities, Available-for-Sale, Unrealized Holding Gain (Loss), before Adjustment, after Tax									(2,614)	(357)	478
Other Comprehensive Income (Loss), Reclassification Adjustment from AOCI for Sale of Securities, Net of Tax									354	(100)	(50)
Change in net unrealized gains/losses on investments									(2,260)	(457)	428
AOCI, Debt Securities, Ending Balance	(1,799)			(2,125)			(1,799)	(2,125)	(1,768)	492	949
OCI, Debt Securities, Available-for-Sale, Gain (Loss), after Adjustment, Tax									926	121	(160)
Reclassification adjustment for net realized loss (gain) on investment securities, tax (benefit) expense	(35)			(21)			(86)	(75)	94	(27)	13
Non-credit components of impairments on investments [Member]
AOCI, Other than Temporary Impairment, Not Credit Loss, Beginning Balance	6		3	2		0	3	0	0	2	2
Change in non-credit component of impairment losses on investments	2			(1)			(1)	(3)	(3)	2	0
AOCI, Other than Temporary Impairment, Not Credit Loss, Ending Balance	4	6		3	2		4	3	3	0	2
Other than Temporary Impairment Losses, Investments, Portion in Other Comprehensive Loss, Tax, Portion Attributable to Parent, Available-for-Sale Securities									0	(1)	0
Net cash flow hedges
AOCI, Cash Flow Hedge, Beginning Balance	(214)		(229)	(233)		(239)	(229)	(239)	(239)	(250)	(262)
Change in net unrealized gains/losses on cash flow hedges	1			2			16	8	10	11	12
AOCI, Cash Flow Hedge, Ending Balance	(213)	(214)		(231)	(233)		(213)	(231)	(229)	(239)	(250)
Other Comprehensive Income (Loss), Cash Flow Hedge, Gain (Loss), after Reclassification, Tax									(6)	(3)	(3)
Pension and other postretirement benefits
AOCI, Defined Benefit Plan, Beginning Balance	(494)		(499)	(413)		(429)	(499)	(429)	(429)	(552)	(551)
Change in net periodic pension and postretirement costs	2			7			7	23	(70)	123	(1)
AOCI, Defined Benefit Plan, Ending Balance	(492)	(494)		(406)	(413)		(492)	(406)	(499)	(429)	(552)
Net change in unrecognized periodic benefit costs for defined benefit pension and postretirement benefit plans, tax expense	0			(3)			(2)	(9)	(23)	(36)	(2)
Future Policy Benefits
AOCI, Liability for Future Policy Benefit, After Tax, Beginning Balance	12		13	(2)		(19)	13	(19)	(19)	0	0
Change in future policy benefits, net of tax	3			7			2	24	32	(7)	0
AOCI, Liability for Future Policy Benefit, After Tax, Ending Balance	15	12		5	(2)		15	5	13	(19)	0
Change in future policy benefits, tax expense	0			2			0	7	(10)	2	0
Future Policy Benefits | Previously Reported [Member]
AOCI, Liability for Future Policy Benefit, After Tax, Beginning Balance										0
AOCI, Liability for Future Policy Benefit, After Tax, Ending Balance											0
Future Policy Benefits | Revision of Prior Period, Accounting Standards Update, Adjustment [Member]
AOCI, Liability for Future Policy Benefit, After Tax, Beginning Balance										(12)
AOCI, Liability for Future Policy Benefit, After Tax, Ending Balance											(12)
Foreign currency translation adjustments
AOCI, Foreign Currency Translation Adjustment, Net of Tax, Beginning Balance	(15)		(17)	(12)		(4)	(17)	(4)	(4)	5	(2)
Foreign currency translation adjustment, net of tax	(4)			(7)			(2)	(15)	(13)	(9)	7
Accumulated Other Comprehensive Income (Loss), Foreign Currency Translation Adjustment, Net of Tax, Ending Balance	(19)	(15)		(19)	(12)		(19)	(19)	(17)	(4)	5
Other Comprehensive Income (Loss), Foreign Currency Translation Adjustment, Tax (Expense) Benefit	1			2			0	4	6	2	$ (2)
AOCI, Accumulated Gain (Loss), Debt Securities, Available-for-Sale, Parent
AOCI, Debt Securities, Beginning Balance	(1,449)		$ (1,755)	(1,489)		$ 494	(1,755)	494	494
OCI, Debt Securities, Available-for-Sale, Unrealized Holding Gain (Loss), before Adjustment, after Tax	(464)			(719)			(317)	(2,914)
Other Comprehensive Income (Loss), Reclassification Adjustment from AOCI for Sale of Securities, Net of Tax	112			80			273	284
Change in net unrealized gains/losses on investments	$ (352)			$ (639)			$ (44)	$ (2,630)
AOCI, Debt Securities, Ending Balance		$ (1,449)			$ (1,489)				$ (1,755)	$ 494