10-K Medical Claims Payable (Short-Duration Insurance Contracts, Claims Development) (Details) - USD ($) $ in Millions	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Medical Claims Payable [Line Items]
Short-Duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net	$ 305,246
Short-Duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	289,904
Commercial and Specialty Business Segment [Member]
Medical Claims Payable [Line Items]
Short-Duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net	305,246
Short-Duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	289,904
Short-Duration Insurance Contracts, Accident Year 2017 | Commercial and Specialty Business Segment [Member]
Medical Claims Payable [Line Items]
Short-Duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net	91,683	$ 91,708	$ 93,410
Short-Duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	91,488	91,151	$ 82,322
Short-duration Insurance Contracts, Accident Year 2019 and Prior Member] | Commercial and Specialty Business Segment [Member]
Medical Claims Payable [Line Items]
Short-Duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net	100,016	100,860
Short-Duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	99,419	$ 88,156
Short-Duration Insurance Contract, Accident Year 2019 [Member] | Commercial and Specialty Business Segment [Member]
Medical Claims Payable [Line Items]
Short-Duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net	113,547
Short-Duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 98,997