Medical Claims Payable Medical Claims Payable (Reconciliation of the Claims Development to the Claims Liability) (Details) - USD ($) $ in Millions	Jun. 30, 2022	Dec. 31, 2021	Jun. 30, 2021	Dec. 31, 2020
Short-duration Insurance Contracts, Reconciliation of Claims Development to Liability [Line Items]
Net medical claims payable, end of period	$ 14,876	$ 13,261		$ 11,089
Ceded medical claims payable end of period	13	21	$ 41	46
Insurance lines other than short duration	238
Gross medical claims payable, end of period	15,127	13,518
Commercial & Specialty Business Segment [Member]
Short-duration Insurance Contracts, Reconciliation of Claims Development to Liability [Line Items]
Net medical claims payable, end of period	4,068	3,834		3,281
Ceded medical claims payable end of period	10	13	11	13
Insurance lines other than short duration	0
Gross medical claims payable, end of period	4,078
Government Business Segment [Member]
Short-duration Insurance Contracts, Reconciliation of Claims Development to Liability [Line Items]
Net medical claims payable, end of period	10,566	9,149		7,613
Ceded medical claims payable end of period	3	8	30	33
Insurance lines other than short duration	238
Gross medical claims payable, end of period	10,807
Other Segment [Member]
Short-duration Insurance Contracts, Reconciliation of Claims Development to Liability [Line Items]
Net medical claims payable, end of period	242	278		195
Ceded medical claims payable end of period	0	$ 0	$ 0	$ 0
Insurance lines other than short duration	0
Gross medical claims payable, end of period	$ 242