Goodwill and Other Intangibles - Intangible Assets (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Other Intangible Assets[Line Items]
Indefinite-lived intangible assets, Trademarks	$ 10,498	$ 10,498
Finite-lived intangible assets, accumulated amortization	(14,932)	(13,028)
Intangible assets, gross	44,166	37,859
Intangible assets, net	$ 29,234	24,803
Intangible assets, net		$ 24,831
Weighted Average Life (years)	14 years 6 months	13 years 10 months 24 days
Disposal Group, Held-for-sale, Not Discontinued Operations
Other Intangible Assets[Line Items]
Intangible assets, net		$ 28
Customer contracts/relationships and covenants not to compete
Other Intangible Assets[Line Items]
Finite-lived intangible assets, gross carrying amount	$ 26,784	21,206
Finite-lived intangible assets, accumulated amortization	(12,241)	(10,668)
Finite-lived intangible assets, net carrying amount	$ 14,543	$ 10,538
Weighted Average Life (years)	14 years 2 months 12 days	13 years 3 months 18 days
Technology
Other Intangible Assets[Line Items]
Finite-lived intangible assets, gross carrying amount	$ 1,253	$ 1,060
Finite-lived intangible assets, accumulated amortization	(1,104)	(1,060)
Finite-lived intangible assets, net carrying amount	$ 149	$ 0
Weighted Average Life (years)	3 years	0 years
Provider networks
Other Intangible Assets[Line Items]
Finite-lived intangible assets, gross carrying amount	$ 4,203	$ 4,203
Finite-lived intangible assets, accumulated amortization	(1,072)	(862)
Finite-lived intangible assets, net carrying amount	$ 3,131	$ 3,341
Weighted Average Life (years)	20 years	20 years
Value of Business Acquired
Other Intangible Assets[Line Items]
Finite-lived intangible assets, gross carrying amount	$ 590	$ 590
Finite-lived intangible assets, accumulated amortization	(201)	(174)
Finite-lived intangible assets, net carrying amount	$ 389	$ 416
Weighted Average Life (years)	20 years	20 years
Other
Other Intangible Assets[Line Items]
Finite-lived intangible assets, gross carrying amount	$ 838	$ 302
Finite-lived intangible assets, accumulated amortization	(314)	(264)
Finite-lived intangible assets, net carrying amount	$ 524	$ 38
Weighted Average Life (years)	9 years 3 months 18 days	12 years 4 months 24 days