v3.25.1
Medical Claims Liability - Narrative (Details) - USD ($)
$ in Millions
3 Months Ended
Mar. 31, 2025
Mar. 31, 2024
Dec. 31, 2024
Dec. 31, 2023
Insurance [Abstract]        
Amounts recorded as an adjustment to premium revenues related to minimum HBR and return of premium programs $ (34) $ (54)    
Short-duration insurance contracts, Incurred but not reported and expected development on reported claims 13,389      
Segment Reporting Information [Line Items]        
Amounts recorded as an adjustment to premium revenues related to minimum HBR and return of premium programs 34 54    
Short-duration insurance contracts, Incurred but not reported and expected development on reported claims 13,389      
Premium deficiency reserve liability 178 50    
Medicare        
Segment Reporting Information [Line Items]        
Premium deficiency reserve liability 178 50    
Medicare | Medicare Advantage 2024        
Segment Reporting Information [Line Items]        
Premium deficiency reserve liability   $ 300   $ 250
Medicare | Medicare Advantage 2025        
Segment Reporting Information [Line Items]        
Premium deficiency reserve liability $ 270   $ 92