v3.26.1
Write-Downs of Long-Lived Assets - Breakdowns of Recognized Impairment Losses for Difference between Carrying Amounts and Fair Values Reflected as Write-Downs of Long-Lived Assets (Detail)
¥ in Millions
 12 Months Ended
Mar. 31, 2026
JPY (¥)
Property
Mar. 31, 2025
JPY (¥)
Property
Mar. 31, 2024
JPY (¥)
Property
Impaired Long-Lived Assets Held and Used [Line Items]      
Write-downs of the assets held for sale, amount ¥ 8,740 ¥ 629 ¥ 134
Write-downs of the assets held for sale, number of properties | Property
Write-downs due to decline in estimated future cash flows, amount ¥ 7,502 ¥ 25,304 ¥ 1,590
Write-downs due to decline in estimated future cash flows, number of properties | Property
Office Buildings      
Impaired Long-Lived Assets Held and Used [Line Items]      
Write-downs of the assets held for sale, amount     ¥ 0
Write-downs due to decline in estimated future cash flows, amount     ¥ 641
Write-downs due to decline in estimated future cash flows, number of properties | Property     2
Commercial facilities other than office buildings      
Impaired Long-Lived Assets Held and Used [Line Items]      
Write-downs of the assets held for sale, amount ¥ 28   ¥ 0
Write-downs of the assets held for sale, number of properties | Property 1    
Write-downs due to decline in estimated future cash flows, amount ¥ 668   ¥ 547
Write-downs due to decline in estimated future cash flows, number of properties | Property 1   4
Condominiums      
Impaired Long-Lived Assets Held and Used [Line Items]      
Write-downs of the assets held for sale, amount ¥ 43 ¥ 31 ¥ 0
Write-downs of the assets held for sale, number of properties | Property 8 20 1
Write-downs due to decline in estimated future cash flows, amount ¥ 0 ¥ 0 ¥ 30
Write-downs due to decline in estimated future cash flows, number of properties | Property 22
Others      
Impaired Long-Lived Assets Held and Used [Line Items]      
Write-downs of the assets held for sale, amount ¥ 8,669 ¥ 598 ¥ 134
Write-downs due to decline in estimated future cash flows, amount ¥ 6,834 ¥ 25,304 ¥ 372