Stock-Based Compensation (Schedule Of Stock Option Activity) (Details) (USD $) In Millions, except Share data in Thousands, unless otherwise specified	3 Months Ended
Jun. 30, 2013
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Exercise Price [Roll Forward]
Options, Outstanding, Beginning Balance	7,802
Options, Granted	4
Options, Exercised	(1,227)
Options, Forfeited, cancelled or expired	(383)
Options, Outstanding, Ending Balance	6,196
Options, Vested and expected to vest	6,165
Options, Exercisable	5,844
Weighted-average exercise price of options outstanding, beginning balance	$ 34.17
Weighted-average exercise price of options granted during period	$ 17.30
Weighted-average exercise price of options exercised during the period	$ 17.55
Weighted-average exercise price of options forfeited, cancelled or expired during the period	$ 46.39
Weighted-average exercise price of options outstanding, ending balance	$ 36.70
Weighted-average exercise price of options vested and expected to vest	$ 36.79
Weighted-average exercise price of options exercisable	$ 37.89
Weighted-average remaining contractual term of options outstanding	4 years 1 month 10 days
Weighted-average remaining contractual term of options vested and expected to vest	4 years 0 months 29 days
Weighted-average remaining contractual term of options exercisable	3 years 10 months 20 days
Aggregate intrinsic value of options outstanding	$ 13
Aggregate intrinsic value of options vested and expected to vest	12
Aggregate intrinsic value of options exercisable	$ 10

Amount of difference between fair value of the underlying shares reserved for issuance and exercise price of vested portions of options outstanding and currently exercisable.

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The number of shares into which fully or partially vested stock options outstanding as of the balance sheet date can be currently converted under the option plan.

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The weighted-average price as of the balance sheet date at which grantees can acquire the shares reserved for issuance on vested portions of options outstanding and currently exercisable under the stock option plan.

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Weighted average remaining contractual term for vested portions of options outstanding and currently exercisable or convertible, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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For presentations that combine terminations, the number of shares under options that were cancelled during the reporting period as a result of occurrence of a terminating event specified in contractual agreements pertaining to the stock option plan or that expired.

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Weighted average price of options that were either forfeited or expired.

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Net number of share options (or share units) granted during the period.

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Amount of difference between fair value of the underlying shares reserved for issuance and exercise price of options outstanding.

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The number of shares reserved for issuance under stock option agreements awarded under the plan that validly exist and are outstanding as of the balance sheet date, including vested options.

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Weighted average price at which grantees can acquire the shares reserved for issuance under the stock option plan.

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Weighted average remaining contractual term for option awards outstanding, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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Amount of difference between fair value of the underlying shares reserved for issuance and exercise price of fully vested and expected to vest options that are exercisable.

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As of the balance sheet date, the number of shares into which fully vested and expected to vest stock options outstanding can be converted under the option plan.

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As of the balance sheet date, the weighted-average exercise price for outstanding stock options that are fully vested or expected to vest.

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Weighted average remaining contractual term for fully vested and expected to vest options outstanding, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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Weighted average price at which option holders acquired shares when converting their stock options into shares.

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Weighted average price at which grantees can acquire the shares reserved for issuance on stock options awarded.

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Number of share options (or share units) exercised during the current period.

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