Debt - Assets and Liabilities Related to Asset-backed Debt Arrangements (Detail) - USD ($) $ in Millions	Jun. 30, 2020	Dec. 31, 2019
Assets and Associated Liabilities of Transfers Accounted for as Secured Borrowings [Line Items]
Account receivable, net	$ 22,672	$ 25,429
Prepaid expenses and other	5,490	8,028
Other assets	10,178	10,141
Accounts payable and accrued liabilities	19,297	21,806
Short-term portion of long-term debt	6,651	10,777
Long-term debt	106,190	100,712
Variable Interest Entity, Primary Beneficiary
Assets and Associated Liabilities of Transfers Accounted for as Secured Borrowings [Line Items]
Account receivable, net	9,981	10,525
Prepaid expenses and other	1,053	1,180
Other assets	3,584	3,856
Accounts payable and accrued liabilities	10	11
Short-term portion of long-term debt	3,894	5,578
Long-term debt	$ 6,713	$ 6,791