Investments in Marketable Securities - Summary of Investments in Marketable Securities (Details) - USD ($) $ in Millions	Sep. 30, 2025	Mar. 31, 2025
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale debt securities, Amortized cost	$ 1,807	$ 1,700
Available-for-sale debt securities, Unrealized gains	14	6
Available-for-sale debt securities, Unrealized losses	(123)	(139)
Available-for-sale debt securities, Fair value	1,698	1,567
Equity investments, Fair value	3,268	3,014
Investments in marketable securities total	4,966	4,581
U.S. government and agency obligations [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale debt securities, Amortized cost	940	824
Available-for-sale debt securities, Unrealized gains	4	2
Available-for-sale debt securities, Unrealized losses	(80)	(83)
Available-for-sale debt securities, Fair value	864	743
Foreign government and agency obligations [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale debt securities, Amortized cost	23	21
Available-for-sale debt securities, Unrealized gains	1	0
Available-for-sale debt securities, Unrealized losses	(1)	(1)
Available-for-sale debt securities, Fair value	23	20
Municipal debt securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale debt securities, Amortized cost	7	8
Available-for-sale debt securities, Unrealized gains	1	1
Available-for-sale debt securities, Unrealized losses	(1)	(1)
Available-for-sale debt securities, Fair value	7	8
Commercial paper [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale debt securities, Amortized cost		15
Available-for-sale debt securities, Unrealized gains		0
Available-for-sale debt securities, Unrealized losses		0
Available-for-sale debt securities, Fair value		15
Corporate debt securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale debt securities, Amortized cost	472	488
Available-for-sale debt securities, Unrealized gains	6	2
Available-for-sale debt securities, Unrealized losses	(30)	(40)
Available-for-sale debt securities, Fair value	448	450
U.S. government agency mortgage-backed securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale debt securities, Amortized cost	137	146
Available-for-sale debt securities, Unrealized gains	1	0
Available-for-sale debt securities, Unrealized losses	(3)	(5)
Available-for-sale debt securities, Fair value	135	141
Non-agency residential mortgage-backed securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale debt securities, Amortized cost	16	12
Available-for-sale debt securities, Unrealized gains	0	0
Available-for-sale debt securities, Unrealized losses	(1)	(1)
Available-for-sale debt securities, Fair value	15	11
Non-agency commercial mortgage-backed securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale debt securities, Amortized cost	51	50
Available-for-sale debt securities, Unrealized gains	0	0
Available-for-sale debt securities, Unrealized losses	(5)	(5)
Available-for-sale debt securities, Fair value	46	45
Asset-backed securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale debt securities, Amortized cost	161	136
Available-for-sale debt securities, Unrealized gains	1	1
Available-for-sale debt securities, Unrealized losses	(2)	(3)
Available-for-sale debt securities, Fair value	$ 160	$ 134

TOYOTA MOTOR CREDIT CORP 10-Q