Stock-Based Compensation (Summary of Stock Option Activity) (Details) (Stock Option [Member], USD $) In Thousands, except Per Share data, unless otherwise specified	6 Months Ended
Sep. 30, 2013
Stock Option [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding [Roll Forward]
Outstanding at the beginning of period, Number Of Stock Options	5,052
Granted, Number Of Stock Options	953
Exercised, Number Of Stock Options	(473)
Forfeited, Number Of Stock Options	(72)
Outstanding at the end of period, Number Of Stock Options	5,460
Vested or expected to vest as of September 30,2013, Number Of Stock Options	5,436
Exercisable as of September 30, 2013, Number Of Stock Options	3,252
Outstanding at the beginning of period, Weighted-Average Exercise Price Per Share	$ 60.26
Granted, Weighted-Average Exercise Price Per Share	$ 102.93
Exercised, Weighted-Average Exercise Price Per Share	$ 49.30
Forfeited, Weighted-Average Exercise Price Per Share	$ 85.24
Outstanding at the end of period, Weighted-Average Exercise Price Per Share	$ 68.33
Vested or expected to vest as of September 30,2013, Weighted-Average Exercise Price Per Share	$ 68.20
Exercisable at September 30, 2013, Weighted-Average Exercise Price Per Share	$ 54.95

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.

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 718

-SubTopic 10

-Section 50

-Paragraph 2

-Subparagraph (c)(1)(iii)

-URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901

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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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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.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 718

-SubTopic 10

-Section 50

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-Subparagraph (c)(1)(iv)(3)

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

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

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Reference 1: http://www.xbrl.org/2003/role/presentationRef

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

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Weighted average price at which grantees could have acquired the underlying shares with respect to stock options that were terminated.

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

+ References

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-Publisher SEC

-Name Regulation S-X (SX)

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-Section 04

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