v3.26.3
Credit Quality of Financial Assets and the Allowance for Credit Losses - Summary of Modifications of Financing Receivables (Detail) - JPY (¥)
¥ in Millions
 6 Months Ended
Sep. 30, 2026
Sep. 30, 2025
Interest rate reduction    
Financing Receivable, Modifications [Line Items]    
Amortized cost basis ¥ 4 ¥ 2,414
% of total class of financing receivable 0.00% 0.00%
Interest rate reduction | Consumer borrowers    
Financing Receivable, Modifications [Line Items]    
Amortized cost basis ¥ 4 ¥ 0
% of total class of financing receivable 0.00% 0.00%
Interest rate reduction | Consumer borrowers | Real estate loans    
Financing Receivable, Modifications [Line Items]    
Amortized cost basis   ¥ 0
% of total class of financing receivable   0.00%
Interest rate reduction | Consumer borrowers | Other    
Financing Receivable, Modifications [Line Items]    
Amortized cost basis ¥ 4 ¥ 0
% of total class of financing receivable 0.00% 0.00%
Interest rate reduction | Corporate borrowers    
Financing Receivable, Modifications [Line Items]    
Amortized cost basis ¥ 0 ¥ 2,414
% of total class of financing receivable 0.00% 0.10%
Interest rate reduction | Corporate borrowers | Non-recourse Loans    
Financing Receivable, Modifications [Line Items]    
Amortized cost basis ¥ 0  
% of total class of financing receivable 0.00%  
Interest rate reduction | Corporate borrowers | Non-recourse Loans | Overseas    
Financing Receivable, Modifications [Line Items]    
Amortized cost basis ¥ 0  
% of total class of financing receivable 0.00%  
Interest rate reduction | Corporate borrowers | Other than non-recourse loans    
Financing Receivable, Modifications [Line Items]    
Amortized cost basis ¥ 0 ¥ 2,414
% of total class of financing receivable 0.00% 0.20%
Interest rate reduction | Corporate borrowers | Other than non-recourse loans | Real estate companies | Japan    
Financing Receivable, Modifications [Line Items]    
Amortized cost basis ¥ 0 ¥ 0
% of total class of financing receivable 0.00% 0.00%
Interest rate reduction | Corporate borrowers | Other than non-recourse loans | Commercial, industrial and other companies | Japan    
Financing Receivable, Modifications [Line Items]    
Amortized cost basis   ¥ 0
% of total class of financing receivable   0.00%
Interest rate reduction | Corporate borrowers | Other than non-recourse loans | Commercial, industrial and other companies | Overseas    
Financing Receivable, Modifications [Line Items]    
Amortized cost basis ¥ 0 ¥ 2,414
% of total class of financing receivable 0.00% 0.40%
Interest rate reduction | Net investment in leases    
Financing Receivable, Modifications [Line Items]    
Amortized cost basis ¥ 0 ¥ 0
% of total class of financing receivable 0.00% 0.00%
Interest rate reduction | Net investment in leases | Japan    
Financing Receivable, Modifications [Line Items]    
Amortized cost basis ¥ 0 ¥ 0
% of total class of financing receivable 0.00% 0.00%
Interest rate reduction | Net investment in leases | Overseas    
Financing Receivable, Modifications [Line Items]    
Amortized cost basis ¥ 0  
% of total class of financing receivable 0.00%  
Term extension    
Financing Receivable, Modifications [Line Items]    
Amortized cost basis ¥ 2,291 ¥ 8,417
% of total class of financing receivable 0.10% 0.20%
Term extension | Consumer borrowers    
Financing Receivable, Modifications [Line Items]    
Amortized cost basis ¥ 0 ¥ 10
% of total class of financing receivable 0.00% 0.00%
Term extension | Consumer borrowers | Real estate loans    
Financing Receivable, Modifications [Line Items]    
Amortized cost basis   ¥ 0
% of total class of financing receivable   0.00%
Term extension | Consumer borrowers | Other    
Financing Receivable, Modifications [Line Items]    
Amortized cost basis ¥ 0 ¥ 10
% of total class of financing receivable 0.00% 0.00%
Term extension | Corporate borrowers    
Financing Receivable, Modifications [Line Items]    
Amortized cost basis ¥ 2,210 ¥ 8,305
% of total class of financing receivable 0.20% 0.40%
Term extension | Corporate borrowers | Non-recourse Loans    
Financing Receivable, Modifications [Line Items]    
Amortized cost basis ¥ 1,848  
% of total class of financing receivable 1.00%  
Term extension | Corporate borrowers | Non-recourse Loans | Overseas    
Financing Receivable, Modifications [Line Items]    
Amortized cost basis ¥ 1,848  
% of total class of financing receivable 1.40%  
Term extension | Corporate borrowers | Other than non-recourse loans    
Financing Receivable, Modifications [Line Items]    
Amortized cost basis ¥ 362 ¥ 8,305
% of total class of financing receivable 0.00% 0.60%
Term extension | Corporate borrowers | Other than non-recourse loans | Real estate companies | Japan    
Financing Receivable, Modifications [Line Items]    
Amortized cost basis ¥ 362 ¥ 289
% of total class of financing receivable 0.30% 0.10%
Term extension | Corporate borrowers | Other than non-recourse loans | Commercial, industrial and other companies | Japan    
Financing Receivable, Modifications [Line Items]    
Amortized cost basis   ¥ 433
% of total class of financing receivable   0.20%
Term extension | Corporate borrowers | Other than non-recourse loans | Commercial, industrial and other companies | Overseas    
Financing Receivable, Modifications [Line Items]    
Amortized cost basis ¥ 0 ¥ 7,583
% of total class of financing receivable 0.00% 1.40%
Term extension | Net investment in leases    
Financing Receivable, Modifications [Line Items]    
Amortized cost basis ¥ 81 ¥ 102
% of total class of financing receivable 0.00% 0.00%
Term extension | Net investment in leases | Japan    
Financing Receivable, Modifications [Line Items]    
Amortized cost basis ¥ 81 ¥ 102
% of total class of financing receivable 0.00% 0.00%
Term extension | Net investment in leases | Overseas    
Financing Receivable, Modifications [Line Items]    
Amortized cost basis ¥ 0  
% of total class of financing receivable 0.00%  
Principal forgiveness    
Financing Receivable, Modifications [Line Items]    
Amortized cost basis ¥ 40 ¥ 12
% of total class of financing receivable 0.00% 0.00%
Principal forgiveness | Consumer borrowers    
Financing Receivable, Modifications [Line Items]    
Amortized cost basis ¥ 0 ¥ 6
% of total class of financing receivable 0.00% 0.00%
Principal forgiveness | Consumer borrowers | Real estate loans    
Financing Receivable, Modifications [Line Items]    
Amortized cost basis   ¥ 6
% of total class of financing receivable   0.00%
Principal forgiveness | Consumer borrowers | Other    
Financing Receivable, Modifications [Line Items]    
Amortized cost basis ¥ 0 ¥ 0
% of total class of financing receivable 0.00% 0.00%
Principal forgiveness | Corporate borrowers    
Financing Receivable, Modifications [Line Items]    
Amortized cost basis ¥ 13 ¥ 6
% of total class of financing receivable 0.00% 0.00%
Principal forgiveness | Corporate borrowers | Non-recourse Loans    
Financing Receivable, Modifications [Line Items]    
Amortized cost basis ¥ 0  
% of total class of financing receivable 0.00%  
Principal forgiveness | Corporate borrowers | Non-recourse Loans | Overseas    
Financing Receivable, Modifications [Line Items]    
Amortized cost basis ¥ 0  
% of total class of financing receivable 0.00%  
Principal forgiveness | Corporate borrowers | Other than non-recourse loans    
Financing Receivable, Modifications [Line Items]    
Amortized cost basis ¥ 13 ¥ 6
% of total class of financing receivable 0.00% 0.00%
Principal forgiveness | Corporate borrowers | Other than non-recourse loans | Real estate companies | Japan    
Financing Receivable, Modifications [Line Items]    
Amortized cost basis ¥ 0 ¥ 0
% of total class of financing receivable 0.00% 0.00%
Principal forgiveness | Corporate borrowers | Other than non-recourse loans | Commercial, industrial and other companies | Japan    
Financing Receivable, Modifications [Line Items]    
Amortized cost basis   ¥ 0
% of total class of financing receivable   0.00%
Principal forgiveness | Corporate borrowers | Other than non-recourse loans | Commercial, industrial and other companies | Overseas    
Financing Receivable, Modifications [Line Items]    
Amortized cost basis ¥ 13 ¥ 6
% of total class of financing receivable 0.00% 0.00%
Principal forgiveness | Net investment in leases    
Financing Receivable, Modifications [Line Items]    
Amortized cost basis ¥ 27 ¥ 0
% of total class of financing receivable 0.00% 0.00%
Principal forgiveness | Net investment in leases | Japan    
Financing Receivable, Modifications [Line Items]    
Amortized cost basis ¥ 0 ¥ 0
% of total class of financing receivable 0.00% 0.00%
Principal forgiveness | Net investment in leases | Overseas    
Financing Receivable, Modifications [Line Items]    
Amortized cost basis ¥ 27  
% of total class of financing receivable 0.00%  
Combination - interest rate reduction and term extension    
Financing Receivable, Modifications [Line Items]    
Amortized cost basis ¥ 2,661 ¥ 49
% of total class of financing receivable 0.10% 0.00%
Combination - interest rate reduction and term extension | Consumer borrowers    
Financing Receivable, Modifications [Line Items]    
Amortized cost basis ¥ 18 ¥ 0
% of total class of financing receivable 0.00% 0.00%
Combination - interest rate reduction and term extension | Consumer borrowers | Real estate loans    
Financing Receivable, Modifications [Line Items]    
Amortized cost basis   ¥ 0
% of total class of financing receivable   0.00%
Combination - interest rate reduction and term extension | Consumer borrowers | Other    
Financing Receivable, Modifications [Line Items]    
Amortized cost basis ¥ 18 ¥ 0
% of total class of financing receivable 0.00% 0.00%
Combination - interest rate reduction and term extension | Corporate borrowers    
Financing Receivable, Modifications [Line Items]    
Amortized cost basis ¥ 2,643 ¥ 49
% of total class of financing receivable 0.20% 0.00%
Combination - interest rate reduction and term extension | Corporate borrowers | Non-recourse Loans    
Financing Receivable, Modifications [Line Items]    
Amortized cost basis ¥ 0  
% of total class of financing receivable 0.00%  
Combination - interest rate reduction and term extension | Corporate borrowers | Non-recourse Loans | Overseas    
Financing Receivable, Modifications [Line Items]    
Amortized cost basis ¥ 0  
% of total class of financing receivable 0.00%  
Combination - interest rate reduction and term extension | Corporate borrowers | Other than non-recourse loans    
Financing Receivable, Modifications [Line Items]    
Amortized cost basis ¥ 2,643 ¥ 49
% of total class of financing receivable 0.30% 0.00%
Combination - interest rate reduction and term extension | Corporate borrowers | Other than non-recourse loans | Real estate companies | Japan    
Financing Receivable, Modifications [Line Items]    
Amortized cost basis ¥ 0 ¥ 0
% of total class of financing receivable 0.00% 0.00%
Combination - interest rate reduction and term extension | Corporate borrowers | Other than non-recourse loans | Commercial, industrial and other companies | Japan    
Financing Receivable, Modifications [Line Items]    
Amortized cost basis   ¥ 0
% of total class of financing receivable   0.00%
Combination - interest rate reduction and term extension | Corporate borrowers | Other than non-recourse loans | Commercial, industrial and other companies | Overseas    
Financing Receivable, Modifications [Line Items]    
Amortized cost basis ¥ 2,643 ¥ 49
% of total class of financing receivable 0.50% 0.00%
Combination - interest rate reduction and term extension | Net investment in leases    
Financing Receivable, Modifications [Line Items]    
Amortized cost basis ¥ 0 ¥ 0
% of total class of financing receivable 0.00% 0.00%
Combination - interest rate reduction and term extension | Net investment in leases | Japan    
Financing Receivable, Modifications [Line Items]    
Amortized cost basis ¥ 0 ¥ 0
% of total class of financing receivable 0.00% 0.00%
Combination - interest rate reduction and term extension | Net investment in leases | Overseas    
Financing Receivable, Modifications [Line Items]    
Amortized cost basis ¥ 0  
% of total class of financing receivable 0.00%  
Combination - interest rate reduction, term extension and principal forgiveness    
Financing Receivable, Modifications [Line Items]    
Amortized cost basis   ¥ 1,201
% of total class of financing receivable   0.00%
Combination - interest rate reduction, term extension and principal forgiveness | Consumer borrowers    
Financing Receivable, Modifications [Line Items]    
Amortized cost basis   ¥ 0
% of total class of financing receivable   0.00%
Combination - interest rate reduction, term extension and principal forgiveness | Consumer borrowers | Real estate loans    
Financing Receivable, Modifications [Line Items]    
Amortized cost basis   ¥ 0
% of total class of financing receivable   0.00%
Combination - interest rate reduction, term extension and principal forgiveness | Consumer borrowers | Other    
Financing Receivable, Modifications [Line Items]    
Amortized cost basis   ¥ 0
% of total class of financing receivable   0.00%
Combination - interest rate reduction, term extension and principal forgiveness | Corporate borrowers    
Financing Receivable, Modifications [Line Items]    
Amortized cost basis   ¥ 1,201
% of total class of financing receivable   0.10%
Combination - interest rate reduction, term extension and principal forgiveness | Corporate borrowers | Other than non-recourse loans    
Financing Receivable, Modifications [Line Items]    
Amortized cost basis   ¥ 1,201
% of total class of financing receivable   0.10%
Combination - interest rate reduction, term extension and principal forgiveness | Corporate borrowers | Other than non-recourse loans | Real estate companies | Japan    
Financing Receivable, Modifications [Line Items]    
Amortized cost basis   ¥ 0
% of total class of financing receivable   0.00%
Combination - interest rate reduction, term extension and principal forgiveness | Corporate borrowers | Other than non-recourse loans | Commercial, industrial and other companies | Japan    
Financing Receivable, Modifications [Line Items]    
Amortized cost basis   ¥ 0
% of total class of financing receivable   0.00%
Combination - interest rate reduction, term extension and principal forgiveness | Corporate borrowers | Other than non-recourse loans | Commercial, industrial and other companies | Overseas    
Financing Receivable, Modifications [Line Items]    
Amortized cost basis   ¥ 1,201
% of total class of financing receivable   0.20%
Combination - interest rate reduction, term extension and principal forgiveness | Net investment in leases    
Financing Receivable, Modifications [Line Items]    
Amortized cost basis   ¥ 0
% of total class of financing receivable   0.00%
Combination - interest rate reduction, term extension and principal forgiveness | Net investment in leases | Japan    
Financing Receivable, Modifications [Line Items]    
Amortized cost basis   ¥ 0
% of total class of financing receivable   0.00%