Financial Instruments
 12 Months Ended
Mar. 31, 2015
Financial Instruments [Abstract]  
Financial Instruments
(3)  FINANCIAL INSTRUMENTS
Cash and Cash Equivalents
As of March 31, 2015 and 2014, our cash and cash equivalents were $2,068 million and $1,782 million, respectively. Cash equivalents were valued at their carrying amounts as they approximate fair value due to the short maturities of these financial instruments.
Short-Term Investments
Short-term investments consisted of the following as of March 31, 2015 and 2014 (in millions):
 
As of March 31, 2015
 
As of March 31, 2014
 
Cost or
Amortized
Cost
 
Gross Unrealized
 
Fair
Value
 
Cost or
Amortized
Cost
 
Gross Unrealized
 
Fair
Value
 
Gains
 
Losses
 
Gains
 
Losses
 
Corporate bonds
$
467

 
$
—

 
$
—

 
$
467

 
$
279

 
$
—

 
$
—

 
$
279

U.S. Treasury securities
214

 
—

 
—

 
214

 
114

 
—

 
—

 
114

U.S. agency securities
161

 
1

 
—

 
162

 
80

 
—

 
—

 
80

Commercial paper
110

 
—

 
—

 
110

 
110

 
—

 
—

 
110

Short-term investments
$
952

 
$
1

 
$
—

 
$
953

 
$
583

 
$
—

 
$
—

 
$
583

We evaluate our investments for impairment quarterly. Factors considered in the review of investments include the credit quality of the issuer, the duration that the fair value has been less than the adjusted cost basis, severity of the impairment, the reason for the decline in value and potential recovery period, the financial condition and near-term prospects of the investees, our intent to sell and ability to hold the investment for a period of time sufficient to allow for any anticipated recovery in market value, and any contractual terms impacting the prepayment or settlement process. Based on our review, we did not consider these investments to be other-than-temporarily impaired as of March 31, 2015 and 2014.
The following table summarizes the amortized cost and fair value of our short-term investments, classified by stated maturity as of March 31, 2015 and 2014 (in millions):
 
As of March 31, 2015
 
As of March 31, 2014
 
Amortized
Cost
 
Fair
Value
 
Amortized
Cost
 
Fair
Value
Short-term investments
 
 
 
 
 
 
 
Due in 1 year or less
$
417

 
$
417

 
$
318

 
$
318

Due in 1-2 years
281

 
281

 
156

 
156

Due in 2-3 years
244

 
245

 
104

 
104

Due in 3-4 years
10

 
10

 
5

 
5

Short-term investments
$
952

 
$
953

 
$
583

 
$
583