Goodwill and Intangible Assets, Net (Information Regarding Intangible Assets) (Details) (USD $) In Millions	6 Months Ended
Sep. 30, 2011	Mar. 31, 2011
Intangible assets
Gross Carrying Amount	$ 2,156	$ 2,136
Accumulated Amortization	(773)	(680)
Net Carrying Amount	1,383	1,456
Customer Lists [Member]
Intangible assets
Weighted Average Remaining Amortization Period (years)	P7Y
Gross Carrying Amount	1,072	1,057
Accumulated Amortization	(498)	(444)
Net Carrying Amount	574	613
Service Agreements [Member]
Intangible assets
Weighted Average Remaining Amortization Period (years)	P17Y
Gross Carrying Amount	696	723
Accumulated Amortization	(34)	(11)
Net Carrying Amount	662	712
Trademarks And Trade Names [Member]
Intangible assets
Weighted Average Remaining Amortization Period (years)	P13Y
Gross Carrying Amount	77	76
Accumulated Amortization	(33)	(31)
Net Carrying Amount	44	45
Technology [Member]
Intangible assets
Weighted Average Remaining Amortization Period (years)	P4Y
Gross Carrying Amount	235	204
Accumulated Amortization	(180)	(170)
Net Carrying Amount	55	34
Other [Member]
Intangible assets
Weighted Average Remaining Amortization Period (years)	P9Y
Gross Carrying Amount	76	76
Accumulated Amortization	(28)	(24)
Net Carrying Amount	$ 48	$ 52

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The accumulated amount of amortization of a major finite-lived intangible asset class. A major class is composed of intangible assets that can be grouped together because they are similar, either by their nature or by their use in the operations of a company.

+ References

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

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 142

-Paragraph 45

-Subparagraph a(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-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009.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 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 350

-SubTopic 30

-Section 50

-Paragraph 2

-Subparagraph (a)(1)

-URI http://asc.fasb.org/extlink&oid=6905858&loc=d3e16323-109275

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- Definition

Sum of the gross carrying amounts before accumulated amortization as of the balance sheet date of all intangible assets having statutory or estimated useful lives. The aggregate gross carrying amount (including any previously recognized impairment charges) of a major finite-lived intangible asset class. A major class is composed of intangible assets that can be grouped together because they are similar, either by their nature or by their use in the operations of a company.

+ References

+ Details

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- Definition

A description of the remaining amortization period of a major finite-lived intangible asset class.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 926

-SubTopic 20

-Section 50

-Paragraph 5

-URI http://asc.fasb.org/extlink&oid=6473108&loc=d3e54445-107959

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- Definition

Sum of the carrying amounts of all intangible assets, excluding goodwill, as of the balance sheet date, net of accumulated amortization and impairment charges.

+ References

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

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 142

-Paragraph 42, 45

-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 Accounting Standards Codification

-Topic 350

-SubTopic 30

-Section 50

-Paragraph 2

-Subparagraph ((a)(1),(b))

-URI http://asc.fasb.org/extlink&oid=6905858&loc=d3e16323-109275

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 350

-SubTopic 30

-Section 45

-Paragraph 1

-URI http://asc.fasb.org/extlink&oid=6388964&loc=d3e16212-109274

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