Income Taxes (Reconciliation Between Effective Tax Rate On Income From Continuing Operations And Statutory Tax Rate) (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
Mar. 31, 2012	Mar. 31, 2011	Mar. 31, 2010
Income Taxes [Abstract]
Income tax provision at federal statutory rate	$ 672	$ 572	$ 652
State and local income taxes net of federal tax benefit	57	33	25
Foreign income taxed at various rates	(176)	(105)	(144)
Unrecognized tax benefits and settlements	(18)	14	53
Tax credits	(13)	(16)	(8)
Other, net	(6)	7	23
Income tax provision	$ 516	$ 505	$ 601

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The sum of the current income tax expense or benefit and the deferred income tax expense or benefit pertaining to continuing operations.

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-Publisher FASB

-Name Accounting Standards Codification

-Glossary Income Tax Expense (or Benefit)

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-Publisher FASB

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-Name Regulation S-X (SX)

-Number 210

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-Name Statement of Financial Accounting Standard (FAS)

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-Subparagraph a, 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-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009.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.

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The portion of the difference, between total income tax expense or benefit as reported in the Income Statement for the period and the expected income tax expense or benefit computed by applying the domestic federal statutory income tax rates to pretax income from continuing operations, that is attributable to total foreign income tax expense or benefit. The foreign income tax expense or benefit difference represents the income tax expense or benefit at applicable domestic statutory income tax rates applied to foreign earnings or loss for the period versus the foreign income tax expense or benefit calculated by applying the appropriate foreign tax rates.

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The amount of income tax expense or benefit for the period computed by applying the domestic federal statutory tax rates to pretax income from continuing operations.

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The sum of other amounts reflected in the reconciliation of the statutory tax provision (benefit) to the actual tax provision (benefit).

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The sum of the differences between total income tax expense or benefit as reported in the Income Statement and the expected income tax expense or benefit computed by applying the domestic federal statutory income tax rates to pretax income from continuing operations attributable to changes in all income tax contingencies, whether recorded or adjusted, during the period.

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The sum of the differences between total income tax expense or benefit as reported in the Income Statement for the period and the expected income tax expense or benefit computed by applying the domestic federal statutory income tax rates to pretax income from continuing operations attributable to tax credits.

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