v3.26.1
Long-Duration Insurance Contracts Relating to Life Insurance Operations - Schedule of Minimum Guaranteed Interest Rates (Detail) - Fixed Annuity - JPY (¥)
¥ in Millions
Mar. 31, 2026
Mar. 31, 2025
Policyholder Account Balance, Guaranteed Minimum Crediting Rate [Line Items]    
Policy holder funds ¥ 101,782 ¥ 119,093
50-150bp    
Policyholder Account Balance, Guaranteed Minimum Crediting Rate [Line Items]    
Policy holder funds 17,947 7,421
150bp and above    
Policyholder Account Balance, Guaranteed Minimum Crediting Rate [Line Items]    
Policy holder funds 286,594 127,151
0.00% – less than 1.50%    
Policyholder Account Balance, Guaranteed Minimum Crediting Rate [Line Items]    
Policy holder funds 94,313 111,626
0.00% – less than 1.50% | 50-150bp    
Policyholder Account Balance, Guaranteed Minimum Crediting Rate [Line Items]    
Policy holder funds 17,947 7,421
0.00% – less than 1.50% | 150bp and above    
Policyholder Account Balance, Guaranteed Minimum Crediting Rate [Line Items]    
Policy holder funds 286,594 127,151
1.50% or more    
Policyholder Account Balance, Guaranteed Minimum Crediting Rate [Line Items]    
Policy holder funds 7,469 7,467
1.50% or more | 50-150bp    
Policyholder Account Balance, Guaranteed Minimum Crediting Rate [Line Items]    
Policy holder funds 0 0
1.50% or more | 150bp and above    
Policyholder Account Balance, Guaranteed Minimum Crediting Rate [Line Items]    
Policy holder funds ¥ 0 ¥ 0