Accounting Policy [Line Items]

No definition available.

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- Definition

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

+ References

No definition available.

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- Definition

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

+ References

No definition available.

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- Definition

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.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 360
-SubTopic 10
-Section 50
-Paragraph 1
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=6391035&loc=d3e2868-110229

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 28
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=66902209&loc=d3e3602-108585

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- Definition

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

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 323
-SubTopic 10
-Section 50
-Paragraph 3
-Subparagraph (a)(1)
-URI http://asc.fasb.org/extlink&oid=66011266&loc=d3e33918-111571

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- Definition

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.

+ References

No definition available.

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Summary of accounting policies - Additional information (Detail) ¥ in Millions	12 Months Ended
	Mar. 31, 2017 JPY (¥)	Mar. 31, 2016 JPY (¥)	Mar. 31, 2015 JPY (¥)
Accounting Policy [Line Items]
Number of business segments	3
Net receivables arising from unsettled securities transactions	¥ 82,672	¥ 161,651
Depreciation and amortization charges of both owned and capital lease assets	70,928	79,394	¥ 78,882
Investments in equity securities	146,730	137,970
Listed equity [Member]
Accounting Policy [Line Items]
Investments in equity securities	107,800	99,203
Unlisted equity [Member]
Accounting Policy [Line Items]
Investments in equity securities	38,930	38,767
Information processing and communications [Member]
Accounting Policy [Line Items]
Depreciation and amortization charges of both owned and capital lease assets	56,186	61,906	59,153
Occupancy and related depreciation [Member]
Accounting Policy [Line Items]
Depreciation and amortization charges of both owned and capital lease assets	¥ 14,742	¥ 17,488	¥ 19,729
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%