Accounting Policy [Line Items]

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Investments in equity securities including investments in equity securities held for relationship purpose following customary business practices in Japan.

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Net receivables arising from unsettled securities transactions reported within Receivables from other than customers

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Amount of the effect of a change in accounting principle on Deferred tax assets.

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New accounting pronouncement or change in accounting principle effect change on other liabilities.

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Amount of the effect of a change in accounting principle on Payables to other than customers.

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The current period expense charged against earnings on long-lived, physical assets not used in production, and which are not intended for resale, to allocate or recognize the cost of such assets over their useful lives; or to record the reduction in book value of an intangible asset over the benefit period of such asset; or to reflect consumption during the period of an asset that is not used in production.

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The percentage of ownership of common stock or equity participation in the investee accounted for under the equity method of accounting.

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Amount of undisbursed portion of the loan receivable balance (loans in process). Excludes loans and leases covered under loss sharing agreements.

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No definition available.

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Amount after allowance and deduction of deferred interest and fees, unamortized costs and premiums and discounts from face amounts, of loans and leases held in portfolio, including but not limited to, commercial and consumer loans. Excludes loans and leases covered under loss sharing agreements and loans held for sale.

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Amount of cumulative effect of the change in accounting principle or new accounting pronouncement on retained earnings or other components of equity or net assets in the statement of financial position as of the beginning of the earliest period presented.

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Number of operating segments. An operating segment is a component of an enterprise: (a) that engages in business activities from which it may earn revenues and incur expenses (including revenues and expenses relating to transactions with other components of the same enterprise), (b) whose operating results are regularly reviewed by the enterprise's chief operating decision maker to make decisions about resources to be allocated to the segment and assess its performance, and (c) for which discrete financial information is available. An operating segment may engage in business activities for which it has yet to earn revenues, for example, start-up operations may be operating segments before earning revenues.

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Amount of liabilities classified as other.

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Amount of expense related to credit loss from transactions other than loan and lease transactions.

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The cumulative amount of the reporting entity's undistributed earnings or deficit.

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Summary of accounting policies - Additional information (Detail) ¥ in Millions		12 Months Ended
	Apr. 01, 2020 JPY (¥)	Mar. 31, 2020 JPY (¥) Segment	Mar. 31, 2019 JPY (¥)	Mar. 31, 2018 JPY (¥)	Apr. 01, 2019 JPY (¥)
Accounting Policy [Line Items]
Number of business segments \| Segment		3
Net receivables arising from unsettled securities transactions		¥ 680,727	¥ 345,850
Depreciation and amortization charges of both owned and capital lease assets		63,583	57,924	¥ 71,579
Investments in equity securities		112,175	138,447
Other liabilities		1,034,448	858,867
Retained earnings		1,645,451	1,486,825
Accounting Standards Update 2016-02 [Member]
Accounting Policy [Line Items]
New accounting standards impact on Payables to other than customers					¥ 169,277
Other liabilities					163,685
Retained earnings					¥ 5,592
Accounting Standards Update 2016-13 [Member]
Accounting Policy [Line Items]
New accounting standards impact on Other liabilities	¥ 638
New accounting standards impact on Deferred tax assets	72
Additional allowances for credit losses	1,972
Retained earnings	(2,538)
Loans receivable	(9,774)
Loan commitment	5,888
Retained earnings	¥ (15,662)
Listed equity [Member]
Accounting Policy [Line Items]
Investments in equity securities		74,755	97,904
Unlisted equity [Member]
Accounting Policy [Line Items]
Investments in equity securities		37,420	40,543
Information processing and communications [Member]
Accounting Policy [Line Items]
Depreciation and amortization charges of both owned and capital lease assets		47,653	45,818	58,300
Occupancy and related depreciation [Member]
Accounting Policy [Line Items]
Depreciation and amortization charges of both owned and capital lease assets		¥ 15,930	¥ 12,106	¥ 13,279
Minimum [Member]
Accounting Policy [Line Items]
Ownership percentage		20.00%
Maximum [Member]
Accounting Policy [Line Items]
Ownership percentage		50.00%
Limited partnership [Member] \| Minimum [Member]
Accounting Policy [Line Items]
Ownership percentage		3.00%