Assets and Liabilities Measured At Fair Value on a Nonrecurring Basis (Detail) (JPY ¥) In Millions, unless otherwise specified	12 Months Ended
Mar. 31, 2013	Mar. 31, 2012
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-lived assets impairments, Amounts included in earnings	¥ (14,494)	¥ (59,583)
Amounts included in earnings	102,722	(17,271)
Level 3 \| Assets Impairment [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-lived assets impairments, Estimated fair value	3,935	8,292
Sony Ericsson
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Remeasurement of previously owned equity interest in Sony Ericsson, Amounts included in earnings		102,331
Sony Ericsson \| Level 3
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Remeasurement of previously owned equity interest in Sony Ericsson, Estimated fair value		71,449
S-LCD
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
S-LCD impairment, Amounts included in earnings		(60,019)
S-LCD \| Level 3 \| Other Than Temporary Impairment Charge [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Equity method investment, Estimated fair value		71,662
M3, Inc.
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Remeasurement of retained investment in M3, Amounts included in earnings	117,216
M3, Inc. \| Level 1
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Equity method investment, Estimated fair value	¥ 128,289

In a business combination achieved in stages, this element represents the amount of net gain (loss) recognized by the entity as a result of remeasuring to fair value the equity interest in the acquiree it held before the business combination.

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In connection with deconsolidation of a subsidiary or derecognition of a group of assets, the portion of any gain (loss) recognized by the parent, during the period, which is related to the remeasurement of any retained investment in the former subsidiary or group of assets to its fair value.

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- Definition

This item represents an other than temporary decline in value that has been recognized against an investment accounted for under the equity method of accounting. The excess of the carrying amount over the fair value of the investment represents the amount of the write down which is or was reflected in earnings. The written down value is a new cost basis with the adjusted value of the investment becoming its new carrying value subject to the equity accounting method. Evidence of a loss in value might include, but would not necessarily be limited to, absence of an ability to recover the carrying amount of the investment or inability of the investee to sustain an earnings capacity which would justify the carrying amount of the investment.

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- Definition

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 investments accounted for under the equity method of accounting as of the balance sheet date.

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