Significant Accounting Policies - Accounts Receivable (Details) - USD ($) $ in Millions	Sep. 30, 2023	Dec. 31, 2022
Accounts, Notes, Loans and Financing Receivable [Line Items]
Trade receivables	$ 10,424	$ 8,983
Vendor and manufacturer receivables	16,646	12,395
Premium receivables	3,254	2,676
Other receivables	2,603	3,449
Total accounts receivable, net	32,927	27,503
Allowance for credit losses	$ 357	333
Disposal Group, Held-for-sale, Not Discontinued Operations
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total accounts receivable, net		$ 227