Significant Accounting Policies - Accounts Receivable (Details) - USD ($) $ in Millions	Sep. 30, 2022	Dec. 31, 2021
Accounts, Notes, Loans and Financing Receivable [Line Items]
Trade receivables	$ 8,016	$ 7,932
Vendor and manufacturer receivables	13,534	10,573
Premium receivables	2,368	2,537
Other receivables	2,647	3,389
Total accounts receivable, net	26,565	24,431
Allowance for credit losses	344	$ 339
Disposal Group, Held-for-sale, Not Discontinued Operations
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total accounts receivable, net	$ 248