Acquisitions, Divestitures and Asset Sales - Schedule of Estimated Fair Values of Assets Acquired and Liabilities Assumed (Details) - USD ($) $ in Millions	Dec. 31, 2023	May 02, 2023	Mar. 29, 2023	Dec. 31, 2022	Dec. 31, 2021
Business Acquisition [Line Items]
Goodwill	$ 91,272			$ 78,150	$ 79,121
Oak Street Health Inc.
Business Acquisition [Line Items]
Cash and cash equivalents		$ 201
Investments		168
Accounts receivable		1,143
Other current assets (including restricted cash)		46
Property and equipment		180
Operating lease right-of-use assets		316
Goodwill		7,213
Intangible assets		4,233
Other long-term assets		7
Total assets acquired		13,507
Health care costs payable		1,098
Other current liabilities		444
Operating lease liabilities (current and long-term)		378
Debt (current and long-term)		1,028
Deferred income taxes		796
Other long-term liabilities		29
Total liabilities assumed		3,773
Noncontrolling interests		66
Total consideration transferred		$ 9,668
Signify Health, Inc.
Business Acquisition [Line Items]
Cash and cash equivalents			$ 376
Accounts receivable			190
Other current assets (including restricted cash)			147
Property and equipment			25
Goodwill			5,909
Intangible assets			1,920
Other long-term assets			23
Total assets acquired			8,590
Other current liabilities			606
Debt (current and long-term)			346
Deferred income taxes			259
Other long-term liabilities			26
Total liabilities assumed			1,237
Total consideration transferred			7,353
Restricted cash			$ 28