Financial Instruments (Tables)

6 Months Ended

Sep. 30, 2013

Financial Instruments [Abstract]

Fair Value Of Short-Term Investments

Short-term investments consisted of the following as of September 30, 2013 and March 31, 2013 (in millions):

	As of September 30, 2013								As of March 31, 2013
	Cost or Amortized Cost		Gross Unrealized				Fair Value		Cost or Amortized Cost		Gross Unrealized				Fair Value
			Gains		Losses						Gains		Losses
Corporate bonds	$	178	$	1	$	—	$	179	$	177	$	1	$	—	$	178
U.S. agency securities	58		—		—		58		76		—		—		76
U.S. Treasury securities	54		—		—		54		85		—		—		85
Commercial paper	37		—		—		37		49		—		—		49
Short-term investments	$	327	$	1	$	—	$	328	$	387	$	1	$	—	$	388

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 September 30, 2013 and March 31, 2013 (in millions):

	As of September 30, 2013				As of March 31, 2013
	Amortized Cost		Fair Value		Amortized Cost		Fair Value
Short-term investments
Due in 1 year or less	$	114	$	114	$	160	$	160
Due in 1-2 years	98		99		126		127
Due in 2-3 years	109		109		101		101
Due in 3-4 years	6		6		—		—
Short-term investments	$	327	$	328	$	387	$	388

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 September 30, 2013 and March 31, 2013 (in millions):

	As of September 30, 2013				As of March 31, 2013
	Carrying Value		Fair Value		Carrying Value		Fair Value
0.75% Convertible Senior Notes due 2016	$	570	$	692	$	559	$	614