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Debt - Additional Information (Detail) (USD $)
In Millions, unless otherwise specified |
9 Months Ended |
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Sep. 30, 2012
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| Debt Instrument [Line Items] | |
| Commercial paper notes | 500.0 |
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Minimum [Member]
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| Debt Instrument [Line Items] | |
| Commercial paper, maturity date | 1 day |
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Maximum [Member]
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| Debt Instrument [Line Items] | |
| Commercial paper, maturity date | 397 days |
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Senior Unsecured Revolving Credit Facility [Member]
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| Debt Instrument [Line Items] | |
| Credit facility borrowing capacity | 500.0 |
| Credit facility expiration date | 2015-02 |
| Line of credit facility, potential maximum borrowing capacity | 750.0 |
| Line of credit facility, available for borrowing | 498.6 |
| X | ||||||||||
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- Definition
Commercial Paper Maturity Period No definition available.
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| X | ||||||||||
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- Definition
Commercial Paper, Maximum Borrowing Capacity No definition available.
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| X | ||||||||||
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- Definition
Debt Instrument, Maturity, Month and Year No definition available.
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| X | ||||||||||
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- Definition
Line of Credit Facility, Potential Maximum Borrowing Capacity No definition available.
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| X | ||||||||||
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- Details
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- Definition
Maximum borrowing capacity under the credit facility without consideration of any current restrictions on the amount that could be borrowed or the amounts currently outstanding under the facility. Reference 1: http://www.xbrl.org/2003/role/presentationRef
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| X | ||||||||||
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- Definition
Amount of borrowing capacity currently available under the credit facility (current borrowing capacity less the amount of borrowings outstanding). Reference 1: http://www.xbrl.org/2003/role/presentationRef
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