Investments in Securities (Gross Unrealized Holding Losses on Investments in Available-for-Sale Securities and Fair Value of Related Investments) (Details) (JPY ¥) In Millions	12 Months Ended
Mar. 31, 2011	Mar. 31, 2010
Available for sale securities, Fair value	¥ 316,560	¥ 383,904
Available for sale securities, Unrealized losses	4,348	900
Equity Securities [Member] \| Continuous Unrealized Loss Position [Member]
Available for sale securities, Fair value	48,891	6,222
Available for sale securities, Unrealized losses	4,342	887
Equity Securities [Member] \| Continuous Unrealized Loss Position [Member] \| Less than 12 Months [Member]
Available for sale securities, Fair value	48,891	6,222
Available for sale securities, Unrealized losses	4,342	887
Corporate and Government Bonds [Member] \| Continuous Unrealized Loss Position [Member]
Available for sale securities, Fair value		1,194
Available for sale securities, Unrealized losses		8
Corporate and Government Bonds [Member] \| Continuous Unrealized Loss Position [Member] \| Less than 12 Months [Member]
Available for sale securities, Fair value		1,194
Available for sale securities, Unrealized losses		8
Other Debt Securities [Member] \| Continuous Unrealized Loss Position [Member]
Available for sale securities, Fair value	35	40
Available for sale securities, Unrealized losses	6	5
Other Debt Securities [Member] \| Continuous Unrealized Loss Position [Member] \| Less than 12 Months [Member]
Available for sale securities, Fair value	35	40
Available for sale securities, Unrealized losses	6	5
Continuous Unrealized Loss Position [Member]
Available for sale securities, Fair value	48,926	7,456
Available for sale securities, Unrealized losses	4,348	900
Continuous Unrealized Loss Position [Member] \| Less than 12 Months [Member]
Available for sale securities, Fair value	48,926	7,456
Available for sale securities, Unrealized losses	4,348	900
Equity Securities [Member]
Available for sale securities, Fair value	313,813	379,358
Available for sale securities, Unrealized losses	4,342	887
Corporate and Government Bonds [Member]
Available for sale securities, Fair value	2,201	3,961
Available for sale securities, Unrealized losses		8
Other Debt Securities [Member]
Available for sale securities, Fair value	546	585
Available for sale securities, Unrealized losses	¥ 6	¥ 5

This element represents the portion of the balance sheet assertion valued at fair value by the entity whether such amount is presented as a separate caption or as a parenthetical disclosure. Additionally, this element may be used in connection with the fair value disclosures required in the footnote disclosures to the financial statements. The element may be used in both the balance sheet and disclosure in the same submission. This item represents Available-for-sale Securities which consist of all investments in certain debt and equity securities neither classified as trading or held-to-maturity securities. A debt security represents a creditor relationship with an enterprise. Debt securities include, among other items, US Treasury securities, US government securities, municipal securities, corporate bonds, convertible debt, commercial paper, and all securitized debt instruments. An equity security represents an ownership interest in an enterprise or the right to acquire or dispose of an ownership interest in an enterprise at fixed or determinable prices. Equity securities include, among other things, common stock, certain preferred stock, warrant rights, call options, and put options, but do not include convertible debt. An entity may opt to provide the reader with additional narrative text to better understand the nature of investments in debt and equity securities which are categorized as Available-for-sale.

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This item represents the gross unrealized losses for securities which are categorized neither as held-to-maturity nor trading securities. Such gross unrealized losses are the excess of the carrying value of the Available-for-sale Securities over their fair value as of the reporting date. Such gross unrealized losses are included in other comprehensive income in the statement of shareholders' equity, unless the Available-for-sale Security is designated as a hedge or is determined to have had an other than temporary decline in fair value below its amortized cost basis. All or a portion of the unrealized holding loss of an Available-for-sale Security that is designated as being hedged in a fair value hedge shall be recognized in earnings during the period of the hedge, as should other than temporary declines in fair value below costs basis.

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