Equity Incentive Plans, Share-based Payment Award (Details) (USD $) In Millions, except Share data, unless otherwise specified	12 Months Ended
Mar. 31, 2013	Mar. 31, 2012	Mar. 31, 2011
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Closing price of company's common stock related to calculation of aggregate intrinsic value of stock options (in dollars per share)	$ 36.77
Restricted stock units' weighted average remaining expense recognition period (in years)	2 years 2 months 8 days
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested [Roll Forward]
RSU nonvested shares beginning balance	5,492,220	5,241,306	4,637,948
RSU shares granted	1,976,583	1,627,191	1,766,257
RSU shares assumed upon acquisition	523,043
RSU shares forfeited/expired	(370,196)	(184,926)	(171,967)
RSU shares vested	(1,611,819)	(1,191,351)	(990,932)
RSU nonvested shares ending balance	6,009,831	5,492,220	5,241,306
Restricted stock units [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total intrinsic value of RSU's vested during the period	$ 54.4	43.7	32.6
Total intrinsic value of RSU's outstanding	$ 221.0
Restricted stock units' weighted average remaining expense recognition period (in years)	2 years 3 months 4 days
Weighted average fair values per share of restricted stock units awarded (amount per share)	$ 29.92	30.48	26.05

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

Weighted average period over which unrecognized compensation is expected to be recognized for equity-based compensation plans, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

+ References

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- Definition

The number of equity-based payment instruments, excluding stock (or unit) options, that were forfeited during the reporting period.

+ References

+ Details

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- Definition

The number of grants made 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

+ Details

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- Definition

The number of non-vested equity-based payment instruments, excluding stock (or unit) options, that validly exist and are outstanding as of the balance sheet date.

+ References

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)(2)(i)-(ii)

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

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

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 123R

-Paragraph A240

-Subparagraph b(2)(b)

-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 Statement of Financial Accounting Standard (FAS)

-Number 123R

-Paragraph A240

-Subparagraph b(2)(a)

-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.

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- Definition

The number of equity-based payment instruments, excluding stock (or unit) options, that vested during the reporting period.

+ References

+ Details

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- Definition

The weighted average fair value as of grant date pertaining to an equity-based award plan other than a stock (or unit) option plan for which the grantee gained the right during the reporting period, by satisfying service and performance requirements, to receive or retain shares or units, other instruments, or cash in accordance with the terms of the arrangement.

+ References

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- Definition

Other increase (decrease) in number of shares reserved for issuance under non-option equity instrument agreements that is not separately disclosed.

+ References

No definition available.

+ 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

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