v3.26.3
Fair Value Measurements (Information about Valuation Techniques and Significant Unobservable Inputs Used in Valuation of Level Three Assets and Liabilities Measured at Fair Value on Recurring Basis) (Detail)
¥ in Millions
Sep. 30, 2026
JPY (¥)
Mar. 31, 2026
JPY (¥)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Loans held for sale ¥ 60,859 ¥ 78,020
Available-for-sale debt securities 2,333,404 2,360,361
Equity securities [1] 639,339 782,137
Derivative assets 60,089 73,633
Other assets 555 1,163
Derivative Liability 48,775 66,802
Policy liabilities and policy account balances 145,670 138,027
Japanese prefectural and foreign municipal bond securities    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Available-for-sale debt securities 272,083 239,545
Corporate debt securities    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Available-for-sale debt securities 867,690 888,919
Other asset-backed securities and debt securities    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Available-for-sale debt securities 160,360 158,528
Level 3    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Available-for-sale debt securities 268,979 260,645
Equity securities 64,129 [2] 230,596 [3]
Fair Value, Measurements, Recurring    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Loans held for sale [4] 60,859 78,020
Available-for-sale debt securities 2,333,404 2,360,361
Derivative assets 60,089 73,633
Other assets 555 1,163
Total 2,868,434 3,095,058
Derivative Liability 48,775 66,802
Policy liabilities and policy account balances 145,670 138,027
Accounts payable 1,574 15,683
Total financial liabilities 240,913 271,768
Fair Value, Measurements, Recurring | Reinsurance recoverables    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Other assets [5] 555 1,163
Fair Value, Measurements, Recurring | Variable annuity and variable life insurance contracts    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Policy liabilities and policy account balances [6] 145,670 138,027
Fair Value, Measurements, Recurring | Japanese prefectural and foreign municipal bond securities    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Available-for-sale debt securities 272,083 239,545
Fair Value, Measurements, Recurring | Corporate debt securities    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Available-for-sale debt securities [7] 867,690 888,919
Fair Value, Measurements, Recurring | Other asset-backed securities and debt securities    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Available-for-sale debt securities 160,360 158,528
Fair Value, Measurements, Recurring | Level 3    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Loans held for sale [4] 21,555 35,684
Available-for-sale debt securities 268,979 260,645
Other assets 555 1,163
Total 363,954 536,075
Policy liabilities and policy account balances 145,670 138,027
Accounts payable 1,574 15,683
Total financial liabilities 155,237 154,267
Fair Value, Measurements, Recurring | Level 3 | Discounted cash flows    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Loans held for sale 21,555 35,684
Fair Value, Measurements, Recurring | Level 3 | Reinsurance recoverables    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Other assets [5] 555 1,163
Fair Value, Measurements, Recurring | Level 3 | Reinsurance recoverables | Discounted cash flows    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Other assets ¥ 555 ¥ 1,163
Fair Value, Measurements, Recurring | Level 3 | Reinsurance recoverables | Annuitization Rate | Discounted cash flows    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Significant unobservable inputs, Other assets 1 1
Fair Value, Measurements, Recurring | Level 3 | Variable annuity and variable life insurance contracts    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Policy liabilities and policy account balances [6] ¥ 145,670 ¥ 138,027
Fair Value, Measurements, Recurring | Level 3 | Variable annuity and variable life insurance contracts | Discounted cash flows    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Policy liabilities and policy account balances 145,670 138,027
Fair Value, Measurements, Recurring | Level 3 | Japanese prefectural and foreign municipal bond securities    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Available-for-sale debt securities 9,172 10,582
Fair Value, Measurements, Recurring | Level 3 | Japanese prefectural and foreign municipal bond securities | Discounted cash flows    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Available-for-sale debt securities 4,913 6,381
Fair Value, Measurements, Recurring | Level 3 | Japanese prefectural and foreign municipal bond securities | Appraisals/Broker quotes    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Available-for-sale debt securities 4,259 4,201
Fair Value, Measurements, Recurring | Level 3 | Corporate debt securities    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Available-for-sale debt securities [7] 116,988 118,191
Fair Value, Measurements, Recurring | Level 3 | Corporate debt securities | Discounted cash flows    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Available-for-sale debt securities 116,662 115,931
Fair Value, Measurements, Recurring | Level 3 | Corporate debt securities | Appraisals/Broker quotes    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Available-for-sale debt securities   1,944
Fair Value, Measurements, Recurring | Level 3 | Corporate debt securities | Discounted cash flows    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Available-for-sale debt securities ¥ 326 ¥ 316
Fair Value, Measurements, Recurring | Level 3 | Corporate debt securities | Discount rate | Discounted cash flows    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Significant unobservable inputs, Available-for-sale debt securities 0.08 0.07
Fair Value, Measurements, Recurring | Level 3 | Corporate debt securities | Discount rate | Discounted cash flows    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Significant unobservable inputs, Available-for-sale debt securities 0.031 0.024
Fair Value, Measurements, Recurring | Level 3 | Corporate debt securities | Equity Volatility | Discounted cash flows    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Significant unobservable inputs, Available-for-sale debt securities 0.50 0.50
Fair Value, Measurements, Recurring | Level 3 | Other asset-backed securities and debt securities    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Available-for-sale debt securities ¥ 142,819 ¥ 131,872
Fair Value, Measurements, Recurring | Level 3 | Other asset-backed securities and debt securities | Discounted cash flows    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Available-for-sale debt securities 36,511 27,094
Fair Value, Measurements, Recurring | Level 3 | Other asset-backed securities and debt securities | Appraisals/Broker quotes    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Available-for-sale debt securities 106,308 104,778
Fair Value, Measurements, Recurring | Level 3 | Investment funds | Discounted cash flows    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Equity securities 5,642 4,800
Fair Value, Measurements, Recurring | Level 3 | Investment funds | Appraisals/Broker quotes    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Equity securities 23,689 22,000
Fair Value, Measurements, Recurring | Level 3 | Investment funds | Market Multiples    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Equity securities 34,798 203,796
Fair Value, Measurements, Recurring | Level 3 | Contingent Consideration | Discounted cash flows    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Accounts payable ¥ 1,574 14,084
Fair Value, Measurements, Recurring | Level 3 | Contingent Consideration | Discounted cash flows    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Accounts payable   ¥ 1,599
Fair Value, Measurements, Recurring | Level 3 | Contingent Consideration | EBTDA Volatility | Discounted cash flows    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Significant unobservable inputs, Accounts Payable 0.35 0.35
Fair Value, Measurements, Recurring | Level 3 | Contingent Consideration | EV/Terminal EBITDA multiple | Discounted cash flows    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Significant unobservable inputs, Accounts Payable   15
Fair Value, Measurements, Recurring | Level 3 | Options held/written and other | Discounted cash flows    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Derivative assets ¥ 8,365 ¥ 7,611
Derivative Liability 7,993 557
Fair Value, Measurements, Recurring | Level 3 | Options held/written and other | Appraisals/Broker quotes    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Derivative assets ¥ 371 ¥ 376
Fair Value, Measurements, Recurring | Level 3 | Minimum | Discount rate | Discounted cash flows    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Significant unobservable inputs, Loans held for sale 0.076 0.061
Fair Value, Measurements, Recurring | Level 3 | Minimum | Reinsurance recoverables | Discount rate | Discounted cash flows    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Significant unobservable inputs, Other assets 0.015 0.011
Fair Value, Measurements, Recurring | Level 3 | Minimum | Reinsurance recoverables | Mortality Rate | Discounted cash flows    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Significant unobservable inputs, Other assets 0 0
Fair Value, Measurements, Recurring | Level 3 | Minimum | Reinsurance recoverables | Lapse Rate | Discounted cash flows    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Significant unobservable inputs, Other assets 0.015 0.015
Fair Value, Measurements, Recurring | Level 3 | Minimum | Variable annuity and variable life insurance contracts | Discount rate | Discounted cash flows    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Significant unobservable inputs, Policy liabilities and Policy Account Balances 0.015 0.011
Fair Value, Measurements, Recurring | Level 3 | Minimum | Variable annuity and variable life insurance contracts | Mortality Rate | Discounted cash flows    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Significant unobservable inputs, Policy liabilities and Policy Account Balances 0 0
Fair Value, Measurements, Recurring | Level 3 | Minimum | Variable annuity and variable life insurance contracts | Lapse Rate | Discounted cash flows    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Significant unobservable inputs, Policy liabilities and Policy Account Balances 0.015 0.015
Fair Value, Measurements, Recurring | Level 3 | Minimum | Variable annuity and variable life insurance contracts | Annuitization Rate | Discounted cash flows    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Significant unobservable inputs, Policy liabilities and Policy Account Balances 0 0
Fair Value, Measurements, Recurring | Level 3 | Minimum | Japanese prefectural and foreign municipal bond securities | Discount rate | Discounted cash flows    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Significant unobservable inputs, Available-for-sale debt securities 0.058 0.036
Fair Value, Measurements, Recurring | Level 3 | Minimum | Other asset-backed securities and debt securities | Discount rate | Discounted cash flows    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Significant unobservable inputs, Available-for-sale debt securities 0.004 0.004
Fair Value, Measurements, Recurring | Level 3 | Minimum | Investment funds | Discount rate | Discounted cash flows    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Significant unobservable inputs, Equity securities 0.11 0.11
Fair Value, Measurements, Recurring | Level 3 | Minimum | Investment funds | EV/Last twelve months EBITDA multiple | Market Multiples    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Significant unobservable inputs, Equity securities 3.5 3.4
Fair Value, Measurements, Recurring | Level 3 | Minimum | Investment funds | EV/Next twelve months EBITDA multiple | Market Multiples    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Significant unobservable inputs, Equity securities 3.3 3.2
Fair Value, Measurements, Recurring | Level 3 | Minimum | Contingent Consideration | Discount rate | Discounted cash flows    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Significant unobservable inputs, Accounts Payable 0.048 0.048
Fair Value, Measurements, Recurring | Level 3 | Minimum | Options held/written and other | Discount rate | Discounted cash flows    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Significant unobservable inputs, Derivative assets 0.12 0.12
Significant unobservable inputs, Derivative liabilities 0.12 0.12
Fair Value, Measurements, Recurring | Level 3 | Maximum | Discount rate | Discounted cash flows    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Significant unobservable inputs, Loans held for sale 0.096 0.099
Fair Value, Measurements, Recurring | Level 3 | Maximum | Reinsurance recoverables | Discount rate | Discounted cash flows    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Significant unobservable inputs, Other assets 0.045 0.035
Fair Value, Measurements, Recurring | Level 3 | Maximum | Reinsurance recoverables | Mortality Rate | Discounted cash flows    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Significant unobservable inputs, Other assets 1 1
Fair Value, Measurements, Recurring | Level 3 | Maximum | Reinsurance recoverables | Lapse Rate | Discounted cash flows    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Significant unobservable inputs, Other assets 0.14 0.14
Fair Value, Measurements, Recurring | Level 3 | Maximum | Variable annuity and variable life insurance contracts | Discount rate | Discounted cash flows    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Significant unobservable inputs, Policy liabilities and Policy Account Balances 0.045 0.035
Fair Value, Measurements, Recurring | Level 3 | Maximum | Variable annuity and variable life insurance contracts | Mortality Rate | Discounted cash flows    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Significant unobservable inputs, Policy liabilities and Policy Account Balances 1 1
Fair Value, Measurements, Recurring | Level 3 | Maximum | Variable annuity and variable life insurance contracts | Lapse Rate | Discounted cash flows    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Significant unobservable inputs, Policy liabilities and Policy Account Balances 0.30 0.30
Fair Value, Measurements, Recurring | Level 3 | Maximum | Variable annuity and variable life insurance contracts | Annuitization Rate | Discounted cash flows    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Significant unobservable inputs, Policy liabilities and Policy Account Balances 1 1
Fair Value, Measurements, Recurring | Level 3 | Maximum | Japanese prefectural and foreign municipal bond securities | Discount rate | Discounted cash flows    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Significant unobservable inputs, Available-for-sale debt securities 0.098 0.098
Fair Value, Measurements, Recurring | Level 3 | Maximum | Other asset-backed securities and debt securities | Discount rate | Discounted cash flows    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Significant unobservable inputs, Available-for-sale debt securities 0.512 0.512
Fair Value, Measurements, Recurring | Level 3 | Maximum | Investment funds | Discount rate | Discounted cash flows    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Significant unobservable inputs, Equity securities 0.115 0.115
Fair Value, Measurements, Recurring | Level 3 | Maximum | Investment funds | EV/Last twelve months EBITDA multiple | Market Multiples    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Significant unobservable inputs, Equity securities 10.5 9
Fair Value, Measurements, Recurring | Level 3 | Maximum | Investment funds | EV/Next twelve months EBITDA multiple | Market Multiples    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Significant unobservable inputs, Equity securities 8.9 8
Fair Value, Measurements, Recurring | Level 3 | Maximum | Contingent Consideration | Discount rate | Discounted cash flows    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Significant unobservable inputs, Accounts Payable 0.05 0.05
Fair Value, Measurements, Recurring | Level 3 | Maximum | Options held/written and other | Discount rate | Discounted cash flows    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Significant unobservable inputs, Derivative assets 0.33 0.33
Significant unobservable inputs, Derivative liabilities 0.33 0.33
Fair Value, Measurements, Recurring | Level 3 | Weighted Average | Discount rate | Discounted cash flows    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Significant unobservable inputs, Loans held for sale 0.082 0.079
Fair Value, Measurements, Recurring | Level 3 | Weighted Average | Reinsurance recoverables | Discount rate | Discounted cash flows    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Significant unobservable inputs, Other assets 0.027 0.02
Fair Value, Measurements, Recurring | Level 3 | Weighted Average | Reinsurance recoverables | Mortality Rate | Discounted cash flows    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Significant unobservable inputs, Other assets 0.028 0.028
Fair Value, Measurements, Recurring | Level 3 | Weighted Average | Reinsurance recoverables | Lapse Rate | Discounted cash flows    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Significant unobservable inputs, Other assets 0.044 0.045
Fair Value, Measurements, Recurring | Level 3 | Weighted Average | Reinsurance recoverables | Annuitization Rate | Discounted cash flows    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Significant unobservable inputs, Other assets 1 1
Fair Value, Measurements, Recurring | Level 3 | Weighted Average | Variable annuity and variable life insurance contracts | Discount rate | Discounted cash flows    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Significant unobservable inputs, Policy liabilities and Policy Account Balances 0.027 0.02
Fair Value, Measurements, Recurring | Level 3 | Weighted Average | Variable annuity and variable life insurance contracts | Mortality Rate | Discounted cash flows    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Significant unobservable inputs, Policy liabilities and Policy Account Balances 0.023 0.023
Fair Value, Measurements, Recurring | Level 3 | Weighted Average | Variable annuity and variable life insurance contracts | Lapse Rate | Discounted cash flows    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Significant unobservable inputs, Policy liabilities and Policy Account Balances 0.055 0.056
Fair Value, Measurements, Recurring | Level 3 | Weighted Average | Variable annuity and variable life insurance contracts | Annuitization Rate | Discounted cash flows    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Significant unobservable inputs, Policy liabilities and Policy Account Balances 0.613 0.644
Fair Value, Measurements, Recurring | Level 3 | Weighted Average | Japanese prefectural and foreign municipal bond securities | Discount rate | Discounted cash flows    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Significant unobservable inputs, Available-for-sale debt securities 0.084 0.08
Fair Value, Measurements, Recurring | Level 3 | Weighted Average | Corporate debt securities | Discount rate | Discounted cash flows    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Significant unobservable inputs, Available-for-sale debt securities 0.08 0.07
Fair Value, Measurements, Recurring | Level 3 | Weighted Average | Corporate debt securities | Discount rate | Discounted cash flows    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Significant unobservable inputs, Available-for-sale debt securities 0.031 0.024
Fair Value, Measurements, Recurring | Level 3 | Weighted Average | Corporate debt securities | Equity Volatility | Discounted cash flows    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Significant unobservable inputs, Available-for-sale debt securities 0.50 0.50
Fair Value, Measurements, Recurring | Level 3 | Weighted Average | Other asset-backed securities and debt securities | Discount rate | Discounted cash flows    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Significant unobservable inputs, Available-for-sale debt securities 0.065 0.068
Fair Value, Measurements, Recurring | Level 3 | Weighted Average | Investment funds | Discount rate | Discounted cash flows    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Significant unobservable inputs, Equity securities 0.113 0.112
Fair Value, Measurements, Recurring | Level 3 | Weighted Average | Investment funds | EV/Last twelve months EBITDA multiple | Market Multiples    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Significant unobservable inputs, Equity securities 8 7.7
Fair Value, Measurements, Recurring | Level 3 | Weighted Average | Investment funds | EV/Next twelve months EBITDA multiple | Market Multiples    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Significant unobservable inputs, Equity securities 4 5.1
Fair Value, Measurements, Recurring | Level 3 | Weighted Average | Contingent Consideration | Discount rate | Discounted cash flows    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Significant unobservable inputs, Accounts Payable 0.049 0.049
Fair Value, Measurements, Recurring | Level 3 | Weighted Average | Contingent Consideration | EBTDA Volatility | Discounted cash flows    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Significant unobservable inputs, Accounts Payable 0.35 0.35
Fair Value, Measurements, Recurring | Level 3 | Weighted Average | Contingent Consideration | EV/Terminal EBITDA multiple | Discounted cash flows    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Significant unobservable inputs, Accounts Payable   15
Fair Value, Measurements, Recurring | Level 3 | Weighted Average | Options held/written and other | Discount rate | Discounted cash flows    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Significant unobservable inputs, Derivative assets 0.148 0.149
Significant unobservable inputs, Derivative liabilities 0.148 0.149
[1] The amount of assets under management of variable annuity and variable life insurance contracts included in equity securities were ¥137,933 million and ¥146,898 million as of March 31, 2026 and September 30, 2026, respectively. The amount of investment funds that elected the fair value option and were included in equity securities were ¥24,845 million and ¥25,231 million as of March 31, 2026 and September 30, 2026, respectively.
[2] The amount of ¥182,674 million of investment funds measured at net asset value per share is not included.
[3] The amount of ¥168,854 million of investment funds measured at net asset value per share is not included.
[4] A certain subsidiary elected the fair value option on certain loans held for sale. These loans are multi-family and seniors housing loans and are sold to Federal National Mortgage Association (“Fannie Mae”), Federal Home Loan Mortgage Corporation (“Freddie Mac”) and institutional investors. Included in “Other (income) and expense” in the consolidated statements of income for the six months ended September 30, 2025 was a loss of ¥1,077 million from the change in the fair value of the loans. For the six months ended September 30, 2026, a loss of ¥3,152 million from the change in the fair value of the loans was included in “Finance revenues.” No gains or losses were recognized in earnings during the six months ended September 30, 2025 and 2026 attributable to changes in instrument-specific credit risk. The amounts of aggregate unpaid principal balance and aggregate fair value of the loans held for sale as of March 31, 2026, were ¥ 79,364 million and ¥ 78,020 million, respectively, and the amount of the aggregate fair value was less than the amount of aggregate unpaid principal balance by ¥ 1,344 million. The amounts of aggregate unpaid principal balance and aggregate fair value of the loans held for sale as of September 30, 2026, were ¥64,741 million and ¥60,859 million, respectively, and the amount of the aggregate fair value was less than the amount of aggregate unpaid principal balance by ¥3,882 million. The amounts of aggregate unpaid principal balance and aggregate fair value of loans that are 90 days or more past due or, in non-accrual status as of March 31, 2026, were ¥9,858 million and ¥8,657 million, respectively, and the amount of the aggregate fair value was less than the amount of aggregate unpaid principal balance by ¥1,201 million. The amounts of aggregate unpaid principal balance and aggregate fair value of loans that are 90 days or more past due or, in non-accrual status as of September 30, 2026, were ¥5,633 million and ¥3,975 million, respectively, and the amount of the aggregate fair value was less than the amount of aggregate unpaid principal balance by ¥1,658 million.
[5] Certain subsidiaries elected the fair value option for certain reinsurance contracts held. The fair value of the reinsurance contracts elected for the fair value option in other assets were ¥1,163 million and ¥555 million as of March 31, 2026 and September 30, 2026, respectively. For the effect of changes in the fair value of those reinsurance contracts on earnings during the six months ended September 30, 2025 and 2026, see Note 17 “Income and Expenses Relating to Life Insurance Operations.”
[6] Certain subsidiaries elected the fair value option for the entire variable annuity and variable life insurance contracts held. The fair value of the variable annuity and variable life insurance contracts elected for the fair value option in policy liabilities and policy account balances were ¥138,027 million and ¥145,670 million as of March 31, 2026 and September 30, 2026, respectively. For the effect of changes in the fair value of the variable annuity and variable life insurance contracts on earnings during the six months ended September 30, 2025 and 2026, see Note 17 “Income and Expenses Relating to Life Insurance Operations.”
[7] A certain subsidiary elected the fair value option for investments in foreign corporate debt securities included in available-for-sale debt securities. Included in “Gains on investment securities and dividends” in the consolidated statements of income were gains of ¥365 million and ¥13 million from the change in the fair value of those investments for the six months ended September 30, 2025 and 2026, respectively. The amounts of aggregate fair value elected the fair value option were ¥11,927 million and ¥9,006 million as of March 31, 2026 and September 30, 2026, respectively.