10-K Income Taxes (Reconciliation Of Income Tax Expense Computed At The Statutory Federal Income Tax Rate) (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Income Tax Disclosure [Abstract]
Amount at statutory rate, amount					$ 1,595	$ 1,679	$ 1,310
Amount at statutory rate, percent					21.00%	21.00%	21.00%
State and local income taxes net of federal tax expense/benefit, amount					$ 236	$ 259	$ 235
State and local income taxes net of federal tax expense/benefit, percent					3.10%	3.30%	3.80%
Tax exempt interest and dividends received deduction, amount					$ (19)	$ (22)	$ (22)
Tax exempt interest and dividends received deduction, percent					(0.30%)	(0.30%)	(0.40%)
Effective Income Tax Reconciliation Patient Protection Affordable Care Act Health Insurance Provider Fee					$ 0	$ 0	$ 330
Health Insurance Provider fee, percent					0.00%	0.00%	5.30%
Basis adjustments from recent acquisitions, amount					$ 0	$ 0	$ (110)
Basis adjustments from recent acquisitions, percent					0.00%	0.00%	(1.80%)
Other, net amount					$ (100)	$ (70)	$ (77)
Other, net percent					(1.30%)	(0.90%)	(1.20%)
Total income tax expense	$ 354	$ 529	$ 1,554	$ 1,544	$ 1,712	$ 1,846	$ 1,666
Effective Income Tax Rate Reconciliation, Percent	21.40%	24.90%	23.10%	23.60%	22.50%	23.10%	26.70%