Fair Value Measurements - Assets and Liabilities Not Carried at Fair Value on Recurring Basis on Consolidated Balance Sheets (Details) - USD ($) $ in Millions	Jun. 30, 2022	Mar. 31, 2022
Unsecured Notes and Loans Payable [Member]
Financial liabilities
Financial liabilities	$ 81,541
Secured Notes and Loans Payable [Member]
Financial liabilities
Financial liabilities	28,882
Fair value [Member] | Unsecured Notes and Loans Payable [Member]
Financial liabilities
Financial liabilities	79,483	$ 80,980
Fair value [Member] | Secured Notes and Loans Payable [Member]
Financial liabilities
Financial liabilities	28,279	26,500
Fair value [Member] | Level 1 [Member] | Unsecured Notes and Loans Payable [Member]
Financial liabilities
Financial liabilities	0	0
Fair value [Member] | Level 1 [Member] | Secured Notes and Loans Payable [Member]
Financial liabilities
Financial liabilities	0	0
Fair value [Member] | Level 2 [Member] | Unsecured Notes and Loans Payable [Member]
Financial liabilities
Financial liabilities	79,483	80,980
Fair value [Member] | Level 2 [Member] | Secured Notes and Loans Payable [Member]
Financial liabilities
Financial liabilities	0	0
Fair value [Member] | Level 3 [Member] | Unsecured Notes and Loans Payable [Member]
Financial liabilities
Financial liabilities	0	0
Fair value [Member] | Level 3 [Member] | Secured Notes and Loans Payable [Member]
Financial liabilities
Financial liabilities	28,279	26,500
Carrying value [Member] | Unsecured Notes and Loans Payable [Member]
Financial liabilities
Financial liabilities		82,288
Carrying value [Member] | Secured Notes and Loans Payable [Member]
Financial liabilities
Financial liabilities		26,864
Retail Loan [Member]
Financial assets
Finance receivables, net	74,472
Retail Loan [Member] | Fair value [Member]
Financial assets
Finance receivables, net	74,886	73,385
Retail Loan [Member] | Fair value [Member] | Level 1 [Member]
Financial assets
Finance receivables, net	0	0
Retail Loan [Member] | Fair value [Member] | Level 2 [Member]
Financial assets
Finance receivables, net	0	0
Retail Loan [Member] | Fair value [Member] | Level 3 [Member]
Financial assets
Finance receivables, net	74,886	73,385
Retail Loan [Member] | Carrying value [Member]
Financial assets
Finance receivables, net		72,369
Wholesale [Member]
Financial assets
Finance receivables, net	2,995
Wholesale [Member] | Fair value [Member]
Financial assets
Finance receivables, net	2,981	2,931
Wholesale [Member] | Fair value [Member] | Level 1 [Member]
Financial assets
Finance receivables, net	0	0
Wholesale [Member] | Fair value [Member] | Level 2 [Member]
Financial assets
Finance receivables, net	0	0
Wholesale [Member] | Fair value [Member] | Level 3 [Member]
Financial assets
Finance receivables, net	2,981	2,931
Wholesale [Member] | Carrying value [Member]
Financial assets
Finance receivables, net		2,940
Real estate [Member]
Financial assets
Finance receivables, net	4,979
Real estate [Member] | Fair value [Member]
Financial assets
Finance receivables, net	4,967	4,961
Real estate [Member] | Fair value [Member] | Level 1 [Member]
Financial assets
Finance receivables, net	0	0
Real estate [Member] | Fair value [Member] | Level 2 [Member]
Financial assets
Finance receivables, net	0	0
Real estate [Member] | Fair value [Member] | Level 3 [Member]
Financial assets
Finance receivables, net	4,967	4,961
Real estate [Member] | Carrying value [Member]
Financial assets
Finance receivables, net		4,985
Working capital [Member]
Financial assets
Finance receivables, net	2,557
Working capital [Member] | Fair value [Member]
Financial assets
Finance receivables, net	2,453	2,171
Working capital [Member] | Fair value [Member] | Level 1 [Member]
Financial assets
Finance receivables, net	0	0
Working capital [Member] | Fair value [Member] | Level 2 [Member]
Financial assets
Finance receivables, net	0	0
Working capital [Member] | Fair value [Member] | Level 3 [Member]
Financial assets
Finance receivables, net	$ 2,453	2,171
Working capital [Member] | Carrying value [Member]
Financial assets
Finance receivables, net		$ 2,256