Allowance for Credit Losses - Additional Information (Details) - Finance Receivables, Net [Member] - USD ($) $ in Millions	Mar. 31, 2019	Mar. 31, 2018
Financing Receivable Allowance For Credit Losses [Line Items]
Ending balance: Collectively evaluated for impairment	$ 71,012	$ 70,320
Retail and Commercial Loan [Member]
Financing Receivable Allowance For Credit Losses [Line Items]
Impaired finance receivables aggregated and collectively evaluated for impairment	231	222
Dealer Products [Member]
Financing Receivable Allowance For Credit Losses [Line Items]
Ending balance: Collectively evaluated for impairment	17,073	16,925
TMNA [Member] | Financial Guarantee [Member] | Dealer Products [Member]
Financing Receivable Allowance For Credit Losses [Line Items]
Ending balance: Collectively evaluated for impairment	1,091	1,030
Private Toyota Distributors [Member] | Financial Guarantee [Member] | Dealer Products [Member]
Financing Receivable Allowance For Credit Losses [Line Items]
Ending balance: Collectively evaluated for impairment	$ 132	$ 146