Medical Claims Payable Medical Claims Payable (Reconciliation of the Claims Development to the Claims Liability) (Details) - USD ($) $ in Millions	3 Months Ended				6 Months Ended
	Jun. 30, 2023	Mar. 31, 2023	Jun. 30, 2022	Mar. 31, 2022	Jun. 30, 2023	Jun. 30, 2022	Dec. 31, 2022	Dec. 31, 2021
Short-duration Insurance Contracts, Reconciliation of Claims Development to Liability [Line Items]
Net medical claims payable, end of period	$ 15,894				$ 15,894		$ 15,342
Ceded medical claims payable end of period	8		$ 13		8	$ 13	6	$ 21
Insurance lines other than short duration	263				263		248
Gross medical claims payable, end of period	16,165				16,165		$ 15,596
Total net incurred medical claims	30,495	$ 29,683	27,634	$ 27,131	60,178	54,765
Quality improvement and other claims expense	1,109	1,103	1,161	1,100	2,212	2,261
Benefit expense	$ 31,604	$ 30,786	$ 28,795	$ 28,231	$ 62,390	$ 57,026