Fair Value Measurements - Assets and Liabilities Not Carried at Fair Value on Recurring Basis on Consolidated Balance Sheets (Details) - USD ($) $ in Millions	Dec. 31, 2025	Mar. 31, 2025
Carrying value [Member] | Unsecured Notes and Loans Payable [Member]
Financial liabilities
Financial liabilities	$ 85,716	$ 90,028
Carrying value [Member] | Secured Notes and Loans Payable [Member]
Financial liabilities
Financial liabilities	36,562	37,717
Fair value [Member] | Unsecured Notes and Loans Payable [Member]
Financial liabilities
Financial liabilities	85,550	89,196
Fair value [Member] | Secured Notes and Loans Payable [Member]
Financial liabilities
Financial liabilities	36,806	37,755
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	85,550	89,196
Fair value [Member] | Level 2 [Member] | Secured Notes and Loans Payable [Member]
Financial liabilities
Financial liabilities	36,806	37,755
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	0	0
Retail Loan [Member] | Carrying value [Member]
Financial assets
Finance receivables, net	82,985	85,633
Retail Loan [Member] | Fair value [Member]
Financial assets
Finance receivables, net	85,791	87,910
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	85,791	87,910
Wholesale [Member] | Carrying value [Member]
Financial assets
Finance receivables, net	7,312	6,512
Wholesale [Member] | Fair value [Member]
Financial assets
Finance receivables, net	7,332	6,538
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	7,332	6,538
Real estate [Member] | Carrying value [Member]
Financial assets
Finance receivables, net	5,865	5,160
Real estate [Member] | Fair value [Member]
Financial assets
Finance receivables, net	5,980	5,215
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	5,980	5,215
Working capital [Member] | Carrying value [Member]
Financial assets
Finance receivables, net	5,354	4,745
Working capital [Member] | Fair value [Member]
Financial assets
Finance receivables, net	5,392	4,727
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	$ 5,392	$ 4,727