Principal Payments Due on Long-Term Borrowings (Detail) (USD $) In Millions, unless otherwise specified	Dec. 31, 2013
Debt Instrument [Line Items]
2014	$ 0
2015	300.0
2016	0
2017	300.0
2018	0
Thereafter	1,500.0
Total	2,100.0
Series 2005-1 Notes
Debt Instrument [Line Items]
2014	0
2015	300.0
2016	0
2017	0
2018	0
Thereafter	0
Total	300.0
Series 2007-1 Notes
Debt Instrument [Line Items]
2014	0
2015	0
2016	0
2017	300.0
2018	0
Thereafter
Total	300.0
2010 Senior Notes
Debt Instrument [Line Items]
2014	0
2015	0
2016	0
2017	0
2018	0
Thereafter	500.0
Total	500.0
2012 Senior Notes
Debt Instrument [Line Items]
2014	0
2015	0
2016	0
2017	0
2018	0
Thereafter	500.0
Total	500.0
2013 Senior Notes
Debt Instrument [Line Items]
2014	0
2015	0
2016	0
2017	0
2018	0
Thereafter	500.0
Total	$ 500.0

Total amount of repayments due on long-term debt

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- Definition

Amount of long-term debt, sinking fund requirements, and other securities redeemable at fixed or determinable prices and dates maturing after the fifth fiscal year following the latest fiscal year.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 470

-SubTopic 10

-Section 50

-Paragraph 1

-URI http://asc.fasb.org/extlink&oid=6802200&loc=d3e1835-112601

Reference 2: 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-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009.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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Amount of long-term debt, sinking fund requirements, and other securities redeemable at fixed or determinable prices and dates maturing in the next fiscal year following the latest fiscal year.

+ References

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Amount of long-term debt, sinking fund requirements, and other securities redeemable at fixed or determinable prices and dates maturing in the fifth fiscal year following the latest fiscal year.

+ References

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Amount of long-term debt, sinking fund requirements, and other securities redeemable at fixed or determinable prices and dates maturing in the fourth fiscal year following the latest fiscal year.

+ References

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Amount of long-term debt, sinking fund requirements, and other securities redeemable at fixed or determinable prices and dates maturing in the third fiscal year following the latest fiscal year.

+ References

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Amount of long-term debt, sinking fund requirements, and other securities redeemable at fixed or determinable prices and dates maturing in the second fiscal year following the latest fiscal year.

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