Stock-Based Compensation (Summary of Stock Option Activity) (Details) (Stock Option [Member], USD $) In Thousands, except Per Share data, unless otherwise specified	9 Months Ended
Dec. 31, 2012
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	6,584
Granted, Number Of Stock Options	966
Exercised, Number Of Stock Options	(2,165)
Forfeited, Number Of Stock Options	(51)
Outstanding at the end of period, Number Of Stock Options	5,334
Vested or expected to vest as of December 31, 2012, Number Of Stock Options	5,315
Exercisable as of December 31, 2012, Number Of Stock Options	2,949
Outstanding at the beginning of period, Weighted-Average Exercise Price Per Share	$ 47.08
Granted, Weighted-Average Exercise Price Per Share	$ 91.52
Exercised, Weighted-Average Exercise Price Per Share	$ 36.13
Forfeited, Weighted-Average Exercise Price Per Share	$ 73.15
Outstanding at the end of period, Weighted-Average Exercise Price Per Share	$ 59.32
Vested or expected to vest as of December 31, 2012, Weighted-Average Exercise Price Per Share	$ 59.23
Exercisable at December 31, 2012, Weighted-Average Exercise Price Per Share	$ 49.04

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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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.

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

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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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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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