Significant Accounting Policies - Narrative (Details) store in Thousands, people in Millions, patient in Millions, $ in Millions	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2024 USD ($) people patient clinic store	Sep. 30, 2023 USD ($)	Sep. 30, 2024 USD ($) people patient state Segment clinic store	Sep. 30, 2023 USD ($)	Dec. 31, 2023 business
Significant Accounting Policies [Line Items]
Number of pharmacy plan members | people	90		90
Number of patients served per year (more than) | patient	0.8		0.8
Number of reportable segments | Segment			4
Number of businesses acquired | business					2
Total premium deficiency reserve		$ 0		$ 0
Medicare Product Line
Significant Accounting Policies [Line Items]
Total premium deficiency reserve	$ 766		$ 766
Premium deficiency reserve, charge for unamortized acquisition costs	383		383
Premium deficiency reserve, charge to health care costs	383		383
Individual Exchange Product Line
Significant Accounting Policies [Line Items]
Total premium deficiency reserve	270		270
Premium deficiency reserve, charge for unamortized acquisition costs	11		11
Premium deficiency reserve, charge to health care costs	259		259
Medicaid Product Line
Significant Accounting Policies [Line Items]
Premium deficiency reserve, charge to health care costs	$ 28		$ 28
Pharmacy & Consumer Wellness
Significant Accounting Policies [Line Items]
Number of retail locations (more than) | store	9		9
Health Services
Significant Accounting Policies [Line Items]
Number of walk in medical clinics (more than) | clinic	900		900
Number of primary care medical clinics (more than) | clinic	225		225
Health Care Benefits
Significant Accounting Policies [Line Items]
Number of people served (more than) | people	36		36
Number of states in which the Company has entered the individual public health insurance exchange | state			17