Write-Downs of Long-Lived Assets - Additional Information (Detail) - JPY (¥) ¥ in Millions	12 Months Ended
Mar. 31, 2026	Mar. 31, 2025	Mar. 31, 2024
Property, Plant and Equipment [Abstract]
Write-downs of long-lived assets	¥ 16,242	¥ 25,933	¥ 1,724

The amount of impairment loss recognized in the period resulting from the write-down of the carrying amount of long-lived assets to fair value.

No definition available.

Name:	ck0001070304_ImpairmentOfWriteDownOfLongLivedAssets
Namespace Prefix:	ck0001070304_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration