Significant Accounting Policies - Narrative (Details) store in Thousands, clinic in Thousands, people in Millions, $ in Millions		3 Months Ended				9 Months Ended
	Sep. 22, 2025 USD ($)	Sep. 30, 2025 USD ($) people store clinic	Jun. 30, 2025 USD ($)	Mar. 31, 2025 USD ($)	Sep. 30, 2024 USD ($)	Sep. 30, 2025 USD ($) people segment clinic store	Sep. 30, 2024 USD ($)	Dec. 31, 2024 USD ($) program
Significant Accounting Policies [Line Items]
Number of pharmacy plan members | people		87				87
Number of reportable segments | segment						4
Allowance for credit losses		$ 178				$ 178		$ 407
Premium deficiency reserve		728			$ 670	728	$ 670
Loss on Accountable Care assets						288
Pre-tax loss on divestiture						236	0
Gain on deconsolidation of subsidiary	$ 483	483			0	483	0
Omnicare, LLC
Significant Accounting Policies [Line Items]
Carrying value and fair value of equity investment		0				0
Individual Exchange Product Line
Significant Accounting Policies [Line Items]
Total premium deficiency reserve charge				$ 448	270
Premium deficiency reserve, charge of unamortized acquisition costs				17	11
Premium deficiency reserve, charge to health care costs				$ 431	259
Premium deficiency reserve		335				335		0
Group Medicare Advantage Product Line
Significant Accounting Policies [Line Items]
Total premium deficiency reserve charge			$ 471
Premium deficiency reserve		$ 393				$ 393
Medicare Product Line
Significant Accounting Policies [Line Items]
Total premium deficiency reserve charge					766		766
Premium deficiency reserve, charge of unamortized acquisition costs					383		383
Premium deficiency reserve, charge to health care costs					383		$ 383
Premium deficiency reserve								0
Medicaid Product Line
Significant Accounting Policies [Line Items]
Premium deficiency reserve, charge to health care costs					$ 28
Premium deficiency reserve								$ 0
Pharmacy & Consumer Wellness
Significant Accounting Policies [Line Items]
Number of retail locations | store		9				9
Health Services
Significant Accounting Policies [Line Items]
Number of walk in medical clinics (more than) | clinic		1				1
Number of programs administered | program								2
Loss on Accountable Care assets						$ 288
Loss on termination of program						52
Health Services | Disposal Group, Disposed of by Sale, Not Discontinued Operations | MSSP
Significant Accounting Policies [Line Items]
Pre-tax loss on divestiture						236
Intangible assets and goodwill removed due to divestiture						$ 342
Health Care Benefits
Significant Accounting Policies [Line Items]
Number of people served (more than) | people		37				37