Medical Claims Payable (Reconciliation Of The Claims Development To The Claims Liability) (Details) - USD ($) $ in Millions	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Short-duration Insurance Contracts, Reconciliation of Claims Development to Liability [Line Items]
Cumulative incurred claims and allocated claim adjustment expenses, net of reinsurance	$ 305,246
Cumulative paid claims and allocated claim adjustment expenses, net of reinsurance	289,904
Net medical claims payable, end of year	15,342
Ceded medical claims payable, end of year	6	$ 21	$ 46	$ 33
Insurance lines other than short duration	248
Gross medical claims payable, end of year	15,596	13,518
Commercial and Specialty Business Segment [Member]
Short-duration Insurance Contracts, Reconciliation of Claims Development to Liability [Line Items]
Cumulative incurred claims and allocated claim adjustment expenses, net of reinsurance	85,128
Cumulative paid claims and allocated claim adjustment expenses, net of reinsurance	81,014
Net medical claims payable, end of year	4,114
Ceded medical claims payable, end of year	5	13	13	14
Insurance lines other than short duration	0
Gross medical claims payable, end of year	4,119
Government Business Segment [Member]
Short-duration Insurance Contracts, Reconciliation of Claims Development to Liability [Line Items]
Cumulative incurred claims and allocated claim adjustment expenses, net of reinsurance	215,498
Cumulative paid claims and allocated claim adjustment expenses, net of reinsurance	204,569
Net medical claims payable, end of year	10,929
Ceded medical claims payable, end of year	1	8	33	19
Insurance lines other than short duration	248
Gross medical claims payable, end of year	11,178
Other Segment [Member]
Short-duration Insurance Contracts, Reconciliation of Claims Development to Liability [Line Items]
Cumulative incurred claims and allocated claim adjustment expenses, net of reinsurance	4,620
Cumulative paid claims and allocated claim adjustment expenses, net of reinsurance	4,321
Net medical claims payable, end of year	299
Ceded medical claims payable, end of year	0	$ 0	$ 0	$ 0
Insurance lines other than short duration	0
Gross medical claims payable, end of year	$ 299