Investments in Securities (Tables)

12 Months Ended

Mar. 31, 2012

Cost, Fair Value, Gross Unrealized Gain (Losses) Of Available-For-Sale Securities

The cost, fair value, gross unrealized holding gains and gross unrealized holding losses of available-for-sale securities included in short-term investments, and other investments and advances at March 31, 2012 and 2011 are as follows:

	Yen (millions)
	2012
	Cost		Fair value		Gross unrealized holding gains		Gross unrealized holding losses
Current:
Other debt securities		473		483		10		—
		473		483		10		—
Noncurrent:
Equity securities		171,412		225,433		54,545		524
Corporate and government bonds		1,689		1,711		22		—
Other debt securities		80		110		30		—
		173,181		227,254		54,597		524
	Yen (millions)
	2011
	Cost		Fair value		Gross unrealized holding gains		Gross unrealized holding losses
Noncurrent:
Equity securities		250,400		313,813		67,755		4,342
Corporate and government bonds		2,142		2,201		59		—
Other debt securities		544		546		8		6
		253,086		316,560		67,822		4,348

Maturities Of Investments In Available-For-Sale Securities

Maturities of investments in available-for-sale securities at March 31, 2012 and 2011 are as follows:

	Yen (millions)
	2012				2011
	Cost		Fair value		Cost		Fair value
Due within one year		473		483		—		—
Due after one year through five years		1,769		1,821		2,686		2,747
Equity securities		171,412		225,433		250,400		313,813
		173,654		227,737		253,086		316,560

Gross Unrealized Holding Losses On Investments In Available-For-Sale Securities And Fair Value Of Related Investments

Gross unrealized holding losses on investments in available-for-sale securities and the fair value of the related investments, aggregated by investment category and length of time that individual securities have been in a continuous unrealized loss position, at March 31, 2012 and 2011 are as follows:

	Yen (millions)
	2012
	Less than 12 months				12 months or more				Total
	Fair value		Unrealized losses		Fair value		Unrealized losses		Fair value		Unrealized losses
Equity securities		5,365		524		—		—		5,365		524
		5,365		524		—		—		5,365		524
	Yen (millions)
	2011
	Less than 12 months				12 months or more				Total
	Fair value		Unrealized losses		Fair value		Unrealized losses		Fair value		Unrealized losses
Equity securities		48,891		4,342		—		—		48,891		4,342
Other debt securities		35		6		—		—		35		6
		48,926		4,348		—		—		48,926		4,348