Equity Incentive Plans, Share-based Payment Award (Details) (USD $) In Millions, except Per Share data, unless otherwise specified	3 Months Ended
Jun. 30, 2012	Jun. 30, 2011
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Amount of unearned share-based compensation estimated to be expensed related to unvested share-based payment awards	$ 70.1
Weighted average period of unearned share-based compensation expected to be recognized (in years)	2.02
Closing price of company's common stock related to calculation of aggregate intrinsic value of restricted stock units (in dollars per share)	$ 33.08
Restricted Stock Units (RSUs) [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Weighted average period of unearned share-based compensation expected to be recognized (in years)	2.04
Total intrinsic value of Restricted Stock Units vested during period	9.8
Total Intrinsic Value Of Restricted Stock Units Outstanding	$ 182.8
Weighted average fair value of restricted stock units awarded in period (amount per share)	$ 31.35	$ 32.95

Closing price per share of company's common stock at balance sheet date

No definition available.

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- Definition

The intrinsic value of share-based payment equity instruments, excluding stock options, outstanding during the reporting period as calculated by applying the disclosed pricing methodology.

+ References

No definition available.

+ Details

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- Definition

As of the balance sheet date, the aggregate unrecognized cost of equity-based awards made to employees under equity-based compensation awards that have yet to vest.

+ References

+ Details

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- Definition

The weighted average period over which unrecognized compensation is expected to be recognized for equity-based compensation plans, using a decimal to express in number of years.

+ References

+ Details

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- Definition

The weighted average fair value at grant date for nonvested equity-based awards issued during the period on other than stock (or unit) option plans (for example, phantom stock or unit plan, stock or unit appreciation rights plan, performance target plan).

+ References

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

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 123R

-Paragraph A240

-Subparagraph b(2)(c)

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 123R

-Paragraph A240

-Subparagraph c(1)

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 718

-SubTopic 10

-Section 50

-Paragraph 2

-Subparagraph (c)(2)(iii)(1)

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

+ Details

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- Definition

The total accumulated difference between fair values of underlying shares on dates of exercise and exercise price on options which were exercised (or share units converted) into shares during the reporting period under the plan.

+ References

+ Details

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