Subsequent Events - Additional Information (Detail) (JPY ¥) In Millions, except Per Share data, unless otherwise specified	12 Months Ended
Mar. 31, 2012
Dividend per common share	¥ 8
Cash dividend per five common shares	¥ 40
Number of common stock eligible for dividend	5
Cash dividends declared	¥ 10,051
Dividends payable, date of record	Mar. 31, 2012
Dividends payable, date declared	May 10, 2012

Common stock dividends per American Depositary Share declared.

No definition available.

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Period Type:	duration

- Definition

The number of common stock that is equal to each American Depositary Share.

+ References

No definition available.

+ Details

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Period Type:	duration

- Definition

The aggregate amount of dividends declared, but not paid, as of the financial reporting date.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 95

-Paragraph 32

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 230

-SubTopic 10

-Section 50

-Paragraph 3

-URI http://asc.fasb.org/extlink&oid=6367179&loc=d3e4304-108586

+ Details

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Balance Type:	credit
Period Type:	instant

- Definition

The per share amount of a dividend declared, but not paid, as of the financial reporting date.

+ References

+ Details

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- Definition

The day, month and year (YYYY-MM-DD) that the dividend to be paid was declared.

+ References

+ Details

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Period Type:	duration

- Definition

The date as of when a holder must own the stock to be entitled to the dividend. The ex-dividend date is generally 3 days before the record date.

+ References

No definition available.

+ Details

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