Financial Instruments (Tables)

12 Months Ended

Mar. 31, 2013

Financial Instruments [Abstract]

Fair Value Of Short-Term Investments

Short-term investments consisted of the following as of March 31, 2013 and 2012 (in millions):

	As of March 31, 2013								As of March 31, 2012
	Cost or Amortized Cost		Gross Unrealized				Fair Value		Cost or Amortized Cost		Gross Unrealized				Fair Value
			Gains		Losses						Gains		Losses
Corporate bonds	$	177	$	1	$	—	$	178	$	149	$	1	$	—	$	150
U.S. Treasury securities	85		—		—		85		166		—		—		166
U.S. agency securities	76		—		—		76		116		—		—		116
Commercial paper	49		—		—		49		5		—		—		5
Short-term investments	$	387	$	1	$	—	$	388	$	436	$	1	$	—	$	437

Fair Value Of Short-Term Investments By Stated Maturity Date Schedule

The following table summarizes the amortized cost and fair value of our short-term investments, classified by stated maturity as of March 31, 2013 and 2012 (in millions):

	As of March 31, 2013				As of March 31, 2012
	Amortized Cost		Fair Value		Amortized Cost		Fair Value
Short-term investments
Due in 1 year or less	$	160	$	160	$	207	$	207
Due in 1-2 years	126		127		123		124
Due in 2-3 years	101		101		106		106
Short-term investments	$	387	$	388	$	436	$	437

Fair Value Of Marketable Equity Securities Schedule

Marketable equity securities consisted of the following as of March 31, 2012 (in millions):

	Adjusted Cost		Gross Unrealized Gains		Gross Unrealized Losses		Fair     Value
As of March 31, 2012	$	32	$	87	$	—	$	119

Carrying Value And Fair Value Of Convertible Senior Notes

The following table summarizes the carrying value and fair value of our 0.75% Convertible Senior Notes due 2016 as of March 31, 2013 and 2012 (in millions):

	As of March 31, 2013				As of March 31, 2012
	Carrying Value		Fair Value		Carrying Value		Fair Value
0.75% Convertible Senior Notes due 2016	$	559	$	614	$	539	$	584