Variable Interest Entity Arrangements - Carrying Values of Assets and Liabilities of Subsidiary in Consolidated Balance Sheets (Detail) - USD ($) $ in Millions	Sep. 30, 2021	Jan. 01, 2021	Dec. 31, 2020	Sep. 30, 2020	Dec. 31, 2019
Current assets
Cash and cash equivalents	$ 16,065		$ 19,384	$ 14,531	$ 6,268
Accounts receivable, net	1,962		1,886
Prepaid expenses and other current assets	1,746		1,346
Total current assets	25,002		26,717
Non-current assets
Other non-current assets	1,854		1,536
Total assets	57,834		52,148
Current liabilities
Accrued liabilities and other	5,443		3,855
Deferred revenue	1,801		1,458
Customer deposits	831		752
Current portion of debt and finance leases	1,716	$ 2,182	2,132
Total current liabilities	18,051		14,248
Deferred revenue, net of current portion	1,365		1,284
Debt and finance leases, net of current portion	6,438	$ 9,775	9,556
Other long-term liabilities	3,486		3,330
Total liabilities	29,340		28,418
Operating Lease Vehicles [Member]
Non-current assets
Operating lease vehicles, net	4,167		3,091
Variable Interest Entities (VIEs) [Member]
Current assets
Cash and cash equivalents	100		87
Accounts receivable, net	44		28
Prepaid expenses and other current assets	144		105
Total current assets	288		220
Non-current assets
Other non-current assets	204		182
Total assets	5,097		5,151
Current liabilities
Accrued liabilities and other	72		63
Deferred revenue	11		11
Customer deposits			14
Current portion of debt and finance leases	1,057		797
Total current liabilities	1,140		885
Deferred revenue, net of current portion	166		168
Debt and finance leases, net of current portion	2,286		1,346
Other long-term liabilities	15		19
Total liabilities	3,607		2,418
Variable Interest Entities (VIEs) [Member] | Solar Energy Systems [Member]
Non-current assets
Operating lease net	$ 4,605		$ 4,749