Segment Reporting and Information about Geographic Areas - Schedule of Total Revenues and Gross Profit by Reportable Segment (Detail) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Segment Reporting Revenue Reconciling Item [Line Items]
Revenues	$ 10,744	$ 8,771	$ 6,036	$ 5,985	$ 7,384	$ 6,303	$ 6,350	$ 4,541	$ 31,536	$ 24,578	$ 21,461
Gross profit	$ 2,066	$ 2,063	$ 1,267	$ 1,234	$ 1,391	$ 1,191	$ 921	$ 566	6,630	4,069	4,042
Automotive Segment [Member]
Segment Reporting Revenue Reconciling Item [Line Items]
Revenues									29,542	23,047	19,906
Gross profit									6,612	3,879	3,852
Energy Generation and Storage [Member]
Segment Reporting Revenue Reconciling Item [Line Items]
Revenues									1,994	1,531	1,555
Gross profit									$ 18	$ 190	$ 190