(Fair Value Of Assets And Liabilities Measured At Fair Value On A Recurring Basis) (Details) - USD ($) $ in Millions		Dec. 31, 2015	Mar. 31, 2015
Fair Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions
Total assets at fair value		$ 1,429	$ 1,211
Total liabilities at fair value		18	18
Quoted Prices In Active Markets For Identical Financial Instruments (Level 1)
Fair Value, Balance Sheet Grouping, Financial Statement Captions
Total assets at fair value		612	405
Total liabilities at fair value		10	9
Significant Other Observable Inputs (Level 2)
Fair Value, Balance Sheet Grouping, Financial Statement Captions
Total assets at fair value		817	806
Total liabilities at fair value		8	9
Fair Value, Inputs, Level 3 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions
Total assets at fair value		0	0
Total liabilities at fair value		0	0
Cash Equivalents | Quoted Prices In Active Markets For Identical Financial Instruments (Level 1) | Bank Time Deposits [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions
Fair value, Cash equivalents		392	175
Cash Equivalents | Quoted Prices In Active Markets For Identical Financial Instruments (Level 1) | Money market funds
Fair Value, Balance Sheet Grouping, Financial Statement Captions
Fair value, Cash equivalents		5	7
Short-Term Investments And Cash Equivalents | Quoted Prices In Active Markets For Identical Financial Instruments (Level 1) | U.S. Treasury securities
Fair Value, Balance Sheet Grouping, Financial Statement Captions
Fair value, Available-for-sale of securities		206
Short-Term Investments And Cash Equivalents | Significant Other Observable Inputs (Level 2) | Corporate bonds
Fair Value, Balance Sheet Grouping, Financial Statement Captions
Fair value, Available-for-sale of securities			468
Short-Term Investments And Cash Equivalents | Significant Other Observable Inputs (Level 2) | U.S. agency securities
Fair Value, Balance Sheet Grouping, Financial Statement Captions
Fair value, Available-for-sale of securities		159	180
Short-Term Investments And Cash Equivalents | Significant Other Observable Inputs (Level 2) | Commercial paper
Fair Value, Balance Sheet Grouping, Financial Statement Captions
Fair value, Available-for-sale of securities		63	140
Short-Term Investments | Quoted Prices In Active Markets For Identical Financial Instruments (Level 1) | U.S. Treasury securities
Fair Value, Balance Sheet Grouping, Financial Statement Captions
Fair value, Available-for-sale of securities			214
Short-Term Investments | Significant Other Observable Inputs (Level 2) | Corporate bonds
Fair Value, Balance Sheet Grouping, Financial Statement Captions
Fair value, Available-for-sale of securities		578
Other Current Assets and Other Assets [Domain] | Significant Other Observable Inputs (Level 2) | Foreign currency derivatives
Fair Value, Balance Sheet Grouping, Financial Statement Captions
Fair value, Foreign currency derivatives, assets		17
Other Current Assets | Significant Other Observable Inputs (Level 2) | Foreign currency derivatives
Fair Value, Balance Sheet Grouping, Financial Statement Captions
Fair value, Foreign currency derivatives, assets			18
Other assets | Quoted Prices In Active Markets For Identical Financial Instruments (Level 1) | Deferred compensation plan assets
Fair Value, Balance Sheet Grouping, Financial Statement Captions
Fair value, Deferred compensation plan assets	[1]	9	9
Accrued and Other Current Liabilities and Other Liabilities | Significant Other Observable Inputs (Level 2) | Foreign currency derivatives
Fair Value, Balance Sheet Grouping, Financial Statement Captions
Fair value, Foreign currency derivatives, liabilities		8
Accrued and Other Current Liabilities | Significant Other Observable Inputs (Level 2) | Foreign currency derivatives
Fair Value, Balance Sheet Grouping, Financial Statement Captions
Fair value, Foreign currency derivatives, liabilities			9
Other liabilities | Quoted Prices In Active Markets For Identical Financial Instruments (Level 1) | Deferred Compensation Plan Liabilities
Fair Value, Balance Sheet Grouping, Financial Statement Captions
Fair value, Deferred compensation plan assets	[1]	$ 10	$ 9

[1] The Deferred Compensation Plan assets consist of various mutual funds. See Note 15 in our Annual Report on Form 10-K for the fiscal year ended March 31, 2015, for additional information regarding our Deferred Compensation Plan.