Summary of Significant Accounting Policies - Schedule of Disaggregation of Revenue by Major Source (Detail) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Disaggregation Of Revenue [Line Items]
Total revenues	$ 11,958	$ 6,036	$ 22,347	$ 12,021
Energy Generation and Storage Sales [Member]
Disaggregation Of Revenue [Line Items]
Total revenues from sales and services	653	225	1,036	398
Services and Other [Member]
Disaggregation Of Revenue [Line Items]
Total revenues from sales and services	951	487	1,844	1,047
Sales and Services [Member]
Disaggregation Of Revenue [Line Items]
Total revenues from sales and services	11,478	5,623	21,459	11,249
Automotive [Member] | Automotive Sales without Resale Value Guarantee [Member]
Disaggregation Of Revenue [Line Items]
Total revenues from sales and services	9,332	4,423	17,345	8,790
Automotive [Member] | Automotive Sales with Resale Value Guarantee [Member]
Disaggregation Of Revenue [Line Items]
Total revenues from sales and services	188	60	362	232
Automotive [Member] | Automotive Regulatory Credits [Member]
Disaggregation Of Revenue [Line Items]
Total revenues from sales and services	354	428	872	782
Automotive [Member] | Automotive Leasing [Member]
Disaggregation Of Revenue [Line Items]
Leasing revenue	332	268	629	507
Energy Generation and Storage [Member]
Disaggregation Of Revenue [Line Items]
Total revenues	801	370	1,295	663
Energy Generation and Storage [Member] | Energy Generation and Storage Leasing [Member]
Disaggregation Of Revenue [Line Items]
Leasing revenue	$ 148	$ 145	$ 259	$ 265