Significant Accounting Policies - Accounts Receivable (Details) - USD ($) $ in Millions	Mar. 31, 2023	Dec. 31, 2022
Accounts, Notes, Loans and Financing Receivable [Line Items]
Trade receivables	$ 9,229	$ 8,983
Vendor and manufacturer receivables	13,357	12,395
Premium receivables	3,636	2,676
Other receivables	2,320	3,449
Total accounts receivable, net	28,542	27,503
Allowance for credit losses	324	333
Disposal Group, Held-for-sale, Not Discontinued Operations
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total accounts receivable, net	$ 211	$ 227