(Schedule Of Stock Option Activity) (Details) $ / shares in Units, shares in Thousands, $ in Millions	12 Months Ended
Mar. 31, 2019 USD ($) $ / shares shares
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding [Roll Forward]
Options, Outstanding, Beginning Balance \| shares	1,615
Options, Granted \| shares	5
Options, Exercised \| shares	(245)
Options, forfeited, cancelled or expired \| shares	0
Options, Outstanding, Ending Balance \| shares	1,375
Options, vested and expected to vest \| shares	1,375
Options, Exercisable \| shares	1,375
Weighted-average exercise price of options outstanding, beginning balance \| $ / shares	$ 30.28
Weighted-average exercise price of options granted during period \| $ / shares	106.55
Weighted-Average Exercise Prices, Exercised during period \| $ / shares	30.00
Weighted-Average Exercise Prices, Forfeited, cancelled or expired during period \| $ / shares	0.00
Weighted-average exercise price of options outstanding, ending balance \| $ / shares	30.63
Weighted-average exercise price of options vested and expected to vest \| $ / shares	30.63
Weighted-average exercise prices of options exercisable \| $ / shares	$ 30.63
Weighted-average remaining contractual term of options outstanding	4 years 8 months 15 days
Weighted-average remaining contractual term of options vested and expected to vest	4 years 8 months 15 days
Weighted-average remaining contractual term of options exercisable	4 years 8 months 15 days
Aggregate intrinsic value of options outstanding \| $	$ 98
Aggregate intrinsic value of options vested and expected to vest \| $	98
Aggregate intrinsic value of options exercisable \| $	$ 98

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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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 by which the current fair value of the underlying stock exceeds the exercise price of options outstanding.

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Number of options outstanding, including both vested and non-vested options.

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Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
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-Section 50
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A roll forward is a reconciliation of a concept from the beginning of a period to the end of a period.

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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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Amount by which current fair value of underlying stock exceeds exercise price of fully vested and expected to vest exercisable or convertible options. Includes, but is not limited to, unvested options for which requisite service period has not been rendered but that are expected to vest based on achievement of performance condition, if forfeitures are recognized when they occur.

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Number of fully vested and expected to vest options outstanding that can be converted into shares under option plan. Includes, but is not limited to, unvested options for which requisite service period has not been rendered but that are expected to vest based on achievement of performance condition, if forfeitures are recognized when they occur.

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Weighted-average exercise price, at which grantee can acquire shares reserved for issuance, for fully vested and expected to vest options outstanding. Includes, but is not limited to, unvested options for which requisite service period has not been rendered but that are expected to vest based on achievement of performance condition, if forfeitures are recognized when they occur.

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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 per share amount at which grantees can acquire shares of common stock by exercise of options.

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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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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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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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Weighted average remaining contractual term for fully vested and expected to vest options outstanding, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents reported fact of one year, five months, and thirteen days. Includes, but is not limited to, unvested options for which requisite service period has not been rendered but that are expected to vest based on achievement of performance condition, if forfeitures are recognized when they occur.

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

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