Fair Value Measurements (Fair Value Of Assets And Liabilities Measured At Fair Value On A Recurring Basis) (Details) (USD $) In Millions, unless otherwise specified	9 Months Ended	12 Months Ended
	Dec. 31, 2012	Mar. 31, 2012	Dec. 31, 2012 Fair Value	Mar. 31, 2012 Fair Value	Dec. 31, 2012 Quoted Prices In Active Markets For Identical Financial Instruments (Level 1)	Mar. 31, 2012 Quoted Prices In Active Markets For Identical Financial Instruments (Level 1)	Dec. 31, 2012 Significant Other Observable Inputs (Level 2)	Mar. 31, 2012 Significant Other Observable Inputs (Level 2)	Dec. 31, 2012 Significant Unobservable Inputs (Level 3)	Mar. 31, 2012 Significant Unobservable Inputs (Level 3)	Dec. 31, 2012 Significant Unobservable Inputs (Level 3) Contingent Consideration	Mar. 31, 2012 Significant Unobservable Inputs (Level 3) Contingent Consideration	Mar. 31, 2011 Significant Unobservable Inputs (Level 3) Contingent Consideration	Dec. 31, 2012 Cash Equivalents Fair Value Money Market Funds	Mar. 31, 2012 Cash Equivalents Fair Value Money Market Funds	Dec. 31, 2012 Cash Equivalents Quoted Prices In Active Markets For Identical Financial Instruments (Level 1) Money Market Funds	Mar. 31, 2012 Cash Equivalents Quoted Prices In Active Markets For Identical Financial Instruments (Level 1) Money Market Funds	Mar. 31, 2012 Short-Term Investments And Cash Equivalents Fair Value U.S. Treasury securities	Dec. 31, 2012 Short-Term Investments And Cash Equivalents Fair Value Commercial Paper	Mar. 31, 2012 Short-Term Investments And Cash Equivalents Fair Value Commercial Paper	Mar. 31, 2012 Short-Term Investments And Cash Equivalents Quoted Prices In Active Markets For Identical Financial Instruments (Level 1) U.S. Treasury securities	Dec. 31, 2012 Short-Term Investments And Cash Equivalents Significant Other Observable Inputs (Level 2) Commercial Paper	Mar. 31, 2012 Short-Term Investments And Cash Equivalents Significant Other Observable Inputs (Level 2) Commercial Paper	Dec. 31, 2012 Short-Term Investments Fair Value Corporate bonds	Mar. 31, 2012 Short-Term Investments Fair Value Corporate bonds	Dec. 31, 2012 Short-Term Investments Fair Value U.S. agency securities	Mar. 31, 2012 Short-Term Investments Fair Value U.S. agency securities	Dec. 31, 2012 Short-Term Investments Fair Value U.S. Treasury securities	Dec. 31, 2012 Short-Term Investments Quoted Prices In Active Markets For Identical Financial Instruments (Level 1) U.S. Treasury securities	Dec. 31, 2012 Short-Term Investments Significant Other Observable Inputs (Level 2) Corporate bonds	Mar. 31, 2012 Short-Term Investments Significant Other Observable Inputs (Level 2) Corporate bonds	Dec. 31, 2012 Short-Term Investments Significant Other Observable Inputs (Level 2) U.S. agency securities	Mar. 31, 2012 Short-Term Investments Significant Other Observable Inputs (Level 2) U.S. agency securities	Dec. 31, 2012 Marketable Equity Securities Fair Value	Mar. 31, 2012 Marketable Equity Securities Fair Value	Dec. 31, 2012 Marketable Equity Securities Quoted Prices In Active Markets For Identical Financial Instruments (Level 1)	Mar. 31, 2012 Marketable Equity Securities Quoted Prices In Active Markets For Identical Financial Instruments (Level 1)	Dec. 31, 2012 Other assets Fair Value Deferred Compensation Plan Assets		Mar. 31, 2012 Other assets Fair Value Deferred Compensation Plan Assets		Dec. 31, 2012 Other assets Quoted Prices In Active Markets For Identical Financial Instruments (Level 1) Deferred Compensation Plan Assets		Mar. 31, 2012 Other assets Quoted Prices In Active Markets For Identical Financial Instruments (Level 1) Deferred Compensation Plan Assets		Dec. 31, 2012 Other current assets Fair Value Foreign Currency Derivatives	Mar. 31, 2012 Other current assets Fair Value Foreign Currency Derivatives	Dec. 31, 2012 Other current assets Significant Other Observable Inputs (Level 2) Foreign Currency Derivatives	Mar. 31, 2012 Other current assets Significant Other Observable Inputs (Level 2) Foreign Currency Derivatives	Dec. 31, 2012 Accrued And Other Current Liabilities And Other Liabilities Fair Value Contingent Consideration		Mar. 31, 2012 Accrued And Other Current Liabilities And Other Liabilities Fair Value Contingent Consideration		Dec. 31, 2012 Accrued And Other Current Liabilities And Other Liabilities Significant Unobservable Inputs (Level 3) Contingent Consideration		Mar. 31, 2012 Accrued And Other Current Liabilities And Other Liabilities Significant Unobservable Inputs (Level 3) Contingent Consideration
Fair Value, Balance Sheet Grouping, Financial Statement Captions
Fair value, Cash equivalents														$ 363	$ 490	$ 363	$ 490
Fair value, Available-for-sale of securities																		170	3	16	170	3	16	149	150	68	116	56	56	149	150	68	116	59	119	59	119
Fair value, Deferred compensation plan assets																																						11	[1]	11	[1]	11	[1]	11	[1]
Fair value, Foreign currency derivatives																																														2	2	2	2
Total assets at fair value			711	1,074	489	790	222	284
Fair value, Contingent consideration																																																		42	[2]	112	[2]	42	[2]	112	[2]
Total liabilities at fair value			42	112					42	112
Fair Value, Measurement with Unobservable Inputs Reconciliations, Recurring Basis, Liability Value											42	112	51
Average Weighted Average Discount Rate	12.00%	12.00%
Business Acquisition, Contingent Consideration, Potential Cash Payment	$ 566	$ 572

[1] The deferred compensation plan assets consist of various mutual funds.

[2] The contingent consideration as of December 31, 2012 and March 31, 2012 represents the estimated fair value of the additional variable cash consideration payable primarily in connection with our acquisitions of PopCap Games, Inc. (“PopCap”), KlickNation Corporation (“KlickNation”), and Chillingo Limited (“Chillingo”) that are contingent upon the achievement of certain performance milestones. We estimated the fair value of the acquisition-related contingent consideration payable using probability-weighted discounted cash flow models, and applied a discount rate that appropriately captures the risk associated with the obligation. The weighted average of the discount rates used during the nine months ended December 31, 2012 and during the fiscal year 2012, was 12 percent. The significant unobservable input used in the fair value measurement of the contingent consideration payable are forecasted earnings. Significant changes in forecasted earnings would result in a significantly higher or lower fair value measurement. At December 31, 2012 and March 31, 2012, the fair market value of acquisition-related contingent consideration totaled $42 million and $112 million, respectively, compared to a maximum potential payout of $566 million and $572 million, respectively. (c)The change in