Long-Term Borrowings (Senior Unsecured Notes Due February 2022) (Detail) (USD $) In Millions, unless otherwise specified	1 Months Ended	12 Months Ended
Feb. 29, 2012	Mar. 31, 2013
Debt Instrument [Line Items]
Debt instrument, maturity date		November 2015
Senior Unsecured Notes Due February 2022 [Member]
Debt Instrument [Line Items]
Senior unsecured debt	$ 500.0
Debt instrument, maturity date		February 2022
Net proceeds after original issuance discount and issuance costs	493.3
Original issuance discount	$ 2.7
Interest rate on senior unsecured notes	4.25%
Redemption options of senior notes		The greater of (i) 100% of the principal amount of these senior notes to be redeemed or (ii) the sum of the present values of the remaining scheduled payments of principal and interest discounted at the applicable United States Treasury rate plus 35 basis points, plus accrued and unpaid interest.
Percentage of principal amount of senior notes to be redeemed		100.00%
Purchase of senior notes at principal plus accrued and unpaid interest		101.00%
Number of basis points to be added to the discounted present value of remaining scheduled payments		0.35%

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Original issuance discount.

+ References

No definition available.

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- Definition

Principal and interest discounted for united states treasury rate.

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- Definition

Redemption of senior notes percentage.

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No definition available.

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- Definition

Redemption Price As Percentage Of Principal Amount And Interest

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- Definition

The stated principal amount of the debt instrument at time of issuance, which may vary from the carrying amount because of unamortized premium or discount.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 835

-SubTopic 30

-Section 45

-Paragraph 2

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-Name Accounting Principles Board Opinion (APB)

-Number 21

-Paragraph 16, 20

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- Definition

Interest rate stated in the contractual debt agreement.

+ References

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

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 02

-Paragraph 22

-Article 5

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-Name Accounting Standards Codification

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- Definition

Disclosure of timing of required repayments, sinking fund requirements, and other redeemable securities at fixed or determinable prices and dates in the five years immediately following the date of the latest balance sheet presented in the financial statements, and the amount thereafter to fully repay the principal of long-term debt. These disclosures may be made either on an individual debt or security basis, by type of debt or security basis, or on a combined basis.

+ References

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

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 47

-Paragraph 10

-Subparagraph 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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-Name Statement of Financial Accounting Standard (FAS)

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-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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-SubTopic 10

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- Definition

The cash inflow from additional borrowings, net of cash paid to third parties in connection with debt origination.

+ References

No definition available.

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