Fair value portion of borrowing which can be exchanged for a specified number of another security at the option of the issuer or the holder, for example, but not limited to, the entity's common stock.

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

-Publisher FASB

-Name Accounting Standards Codification

-Glossary Convertible Security

-URI http://asc.fasb.org/extlink&oid=6509036

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- Definition

Face (par) amount of debt instrument at time of issuance.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 835

-SubTopic 30

-Section 45

-Paragraph 2

-URI http://asc.fasb.org/extlink&oid=6451184&loc=d3e28551-108399

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 835

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-Section 55

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- Definition

The cash outflow from the repayment of a long-term debt instrument which can be exchanged for a specified amount of another security, typically the entity's common stock, at the option of the issuer or the holder.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 230

-SubTopic 10

-Section 45

-Paragraph 15

-Subparagraph (b)

-URI http://asc.fasb.org/extlink&oid=56944662&loc=d3e3291-108585

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

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-Name Accounting Standards Codification

-Glossary Financing Activities

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Fair Value of Financial Instruments (Details) (USD $)	12 Months Ended
Fair Value of Financial Instruments (Details) (USD $)	Mar. 31, 2015	Mar. 31, 2014	Mar. 31, 2013
Debt Instrument [Line Items]
Payment to retire $575 million aggregate principal amount of junior convertible debentures	$ 1,134,621,000us-gaap_RepaymentsOfConvertibleDebt	$ 0us-gaap_RepaymentsOfConvertibleDebt	$ 0us-gaap_RepaymentsOfConvertibleDebt
Senior Subordinated Convertible Debentures Due 2025 [Member]
Debt Instrument [Line Items]
Fair value of convertible debentures based on the trading price of the bonds	1,788,000,000
Junior Subordinated Convertible Debentures Due2037 Member
Debt Instrument [Line Items]
Fair value of convertible debentures based on the trading price of the bonds	1,124,000,000
Principal amount of junior subordinated convertible debentures	575,000,000
Payment to retire $575 million aggregate principal amount of junior convertible debentures	$ 1,134,600,000