Investment in Direct Financing Leases - Additional Information (Detail) - JPY (¥) ¥ in Millions	12 Months Ended
Mar. 31, 2015	Mar. 31, 2014	Mar. 31, 2013
Lease Disclosure [Line Items]
Direct financing leases revenues	¥ 61,116	¥ 57,483	¥ 54,356
Finance Revenues
Lease Disclosure [Line Items]
Direct financing leases revenues	¥ 61,116	¥ 57,483	¥ 54,356

Revenue realized in the period on direct financing leases.

No definition available.

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Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration