Medical Claims Liability - Narrative (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2025	Sep. 30, 2024	Sep. 30, 2025	Sep. 30, 2024	Jun. 30, 2025	Mar. 31, 2025	Dec. 31, 2024	Jun. 30, 2024	Mar. 31, 2024	Dec. 31, 2023
Insurance [Abstract]
Amounts recorded as an adjustment to premium revenues related to minimum HBR and return of premium programs			$ (86)	$ (236)
Short-duration insurance contracts, Incurred but not reported and expected development on reported claims	$ 13,947		13,947
Segment Reporting Information [Line Items]
Amounts recorded as an adjustment to premium revenues related to minimum HBR and return of premium programs			86	236
Short-duration insurance contracts, Incurred but not reported and expected development on reported claims	13,947		13,947
Premium deficiency reserve	190	$ (5)	190	(5)
Medicare
Segment Reporting Information [Line Items]
Premium deficiency reserve	190	(5)	190	(5)
Medicare \| Medicare Advantage 2025
Segment Reporting Information [Line Items]
Premium deficiency reserve	282		$ 282		$ 389	$ 270	$ 92
Premium deficiency reserve increase (decrease)	$ (107)
Medicare \| Medicare Advantage 2024
Segment Reporting Information [Line Items]
Premium deficiency reserve		245		$ 245				$ 335	$ 300	$ 250
Premium deficiency reserve increase (decrease)		$ (90)

CENTENE CORP 10-Q