Significant Accounting Policies - Narrative (Details) people in Millions, patient in Millions, $ in Millions	1 Months Ended	3 Months Ended		9 Months Ended		12 Months Ended
	Jan. 31, 2023 state	Sep. 30, 2022 USD ($) clinic patient people state store	Sep. 30, 2021 USD ($)	Sep. 30, 2022 USD ($) clinic patient people state Segment store	Sep. 30, 2021 USD ($)	Dec. 31, 2023 state
Significant Accounting Policies [Line Items]
Number of pharmacy plan members | people		110		110
Number of patients served per year | patient		1		1
Number of reportable segments | Segment				4
Expenses from transactions with related party | $		$ 16	$ 16	$ 47	$ 35
Other revenues from transactions with related party | $		$ 22	$ 20	$ 66	$ 57
Heartland Healthcare Services
Significant Accounting Policies [Line Items]
Number of states in which entity operates		4		4
Retail/ LTC
Significant Accounting Policies [Line Items]
Number of retail locations (more than) | store		9,000		9,000
Number of walk in medical clinics | clinic		1,100		1,100
Health Care Benefits
Significant Accounting Policies [Line Items]
Number of people served | people		35		35
Number of states in which the Company has entered the individual public health insurance exchange				8
Health Care Benefits | Forecast
Significant Accounting Policies [Line Items]
Number of states in which the Company has entered the individual public health insurance exchange						12
Additional number of states in which the Company will enter the individual public health insurance exchange	4