Acquisitions and Assets Held for Sale - Summary of the Preliminary Valuation of Goodwill Allocated to Business Segments (Details) - USD ($) $ in Millions	Sep. 30, 2023	May 02, 2023	Mar. 29, 2023	Dec. 31, 2022
Business Acquisition [Line Items]
Goodwill	$ 91,261			$ 78,150
Oak Street Health Inc.
Business Acquisition [Line Items]
Goodwill		$ 7,189
Oak Street Health Inc. | Health Services
Business Acquisition [Line Items]
Goodwill		6,912
Oak Street Health Inc. | Pharmacy & Consumer Wellness
Business Acquisition [Line Items]
Goodwill		156
Oak Street Health Inc. | Health Care Benefits
Business Acquisition [Line Items]
Goodwill		$ 121
Signify Health, Inc.
Business Acquisition [Line Items]
Goodwill			$ 5,922
Signify Health, Inc. | Health Services
Business Acquisition [Line Items]
Goodwill			3,419
Signify Health, Inc. | Pharmacy & Consumer Wellness
Business Acquisition [Line Items]
Goodwill			30
Signify Health, Inc. | Health Care Benefits
Business Acquisition [Line Items]
Goodwill			$ 2,473